Ruben2020, and who ever might be interested in answers of you question:
Begin a time where the matter of "what makes one a stream-winner" seems to interest many and maybe because many "Noble-Born" are currently remind, meting they reminder, on their old path they have already gone, it's maybe worthy to recollect the teachings informations about this matter in a good manner and everybody should be encouraged here to point out possible mistakes and missing points.
❋ - Namo tassa bhagavato arahato sammā-sambuddhassa - ❋
➨ 1. How does a reborn stream-winner know that he or she is one?
Acutally in the frame set of the questions it would be unlikely the first, since why would one raise such a question if maybe not even aware of such as "steam-winner.
How ever, lets look what are the atributes that a Streamwinner "possesses". Of what [i]we[/i] know about what the Buddha said, being answered the question, "How does one know if having won the Stream or not?", the properly most similar question and most direct answer is found in the Maha-parinibbana Sutta, in an conversation mit Ven. Ananda Thera, the Bhikkhus have been used to ask for the attainments of others the Lord Buddha an he giving them a mirror to use to look for oneself:
The Mirror of the Dhamma
Ananda, I will give you the teaching called the Mirror of the Dhamma, possessing which the noble disciple, should he so desire, can declare of himself: 'There is no more rebirth for me in hell, nor as an animal or ghost, nor in any realm of woe. A stream-enterer am I, safe from falling into the states of misery, assured am I and bound for Enlightenment.'"
"And what, Ananda, is that teaching called the Mirror of Dhamma, possessing which the noble disciple may thus declare of himself?
"In this case, Ananda, the noble disciple possesses unwavering faith in the Buddha thus: 'The Blessed One is an Arahant, the Fully Enlightened One, perfect in knowledge and conduct, the Happy One, the knower of the world, the paramount trainer of beings, the teacher of gods and men, the Enlightened One, the Blessed One.'
"He possesses unwavering faith in the Dhamma thus: 'Well propounded by the Blessed One is the Dhamma, evident, timeless,  inviting investigation, leading to emancipation, to be comprehended by the wise, each for himself.'
"He possesses unwavering faith in the Blessed One's Order of Disciples thus: 'Well faring is the Blessed One's Order of Disciples, righteously, wisely, and dutifully: that is to say, the four pairs of men, the eight classes of persons. The Blessed One's Order of Disciples is worthy of honor, of hospitality, of offerings, of veneration — the supreme field for meritorious deeds in the world.'
"And he possesses virtues that are dear to the Noble Ones, complete and perfect, spotless and pure, which are liberating, praised by the wise, uninfluenced (by worldly concerns), and favorable to concentration of mind.
"This, Ananda, is the teaching called the Mirror of the Dhamma, whereby the noble disciple may thus know of himself: 'There is no more rebirth for me in hell, nor as an animal or ghost, nor in any realm of woe. A stream-enterer am I, safe from falling into the states of misery, assured am I and bound for Enlightenment.'"
There are other Suttas as well, which describe the attributs of a Streamwinner like in the Samyutta Nikaya, the SN 22.109: Sotaapanno Sutta — The Sotaapanna (' Stream-winner') or the Okkanta-samyutta — Entering
In this samyutta the Buddha explains the kinds of conviction and understanding that are required for the attainment of stream-entry. These short suttas share an identical structure, with each one focusing on a different aspect of experience (including the six senses, the six elements (dhatu), and the five aggregates). See also the Study Guides on stream-entry.
Cakkhu Sutta: The Eye
At Savatthi. "Monks, the eye is inconstant, changeable, alterable. The ear... The nose... The tongue... The body... The mind is inconstant, changeable, alterable.
"One who has conviction & belief that these phenomena are this way is called a faith-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry shades. He is incapable of passing away until he has realized the fruit of stream-entry.
"One who, after pondering with a modicum of discernment, has accepted that these phenomena are this way is called a Dhamma-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry shades. He is incapable of passing away until he has realized the fruit of stream-entry.
"One who knows and sees that these phenomena are this way is called a stream-enterer, steadfast, never again destined for states of woe, headed for self-awakening."
Itks maybe worthy to keep in mind that one needs to be very honest and proof very in detail all corners and dismantel any kind of quickly made judgement in its seriousity. That, how ever, requires to know, heaving heard the good teachings and understand clearly their meaning.
In regard of the fetters, a stream-winner has abounded the first three lower fetters of the ten fetters:
Self-identity views (sakkāya-diṭṭhi), identifying either the clinging-aggragats, or some, or one, or the sense-groups and their objects, some, or one, as being an lasting personality
Uncertainty or doubt (vicikiccha), meaning that one does no more seek for other teachers and teaching than the Buddha and his Dhamma, transported by the Savaka-Sangha.
Grasping at (wrong) precepts & practices (sīlabbata-parāmāsa), which are not conductive for the path and naturally follow conductive ones, relaying merely on the judgement of the own mind in regard of what is skillful and unskilful and no more need of authority be given precepts & practices in the judgements sphere of speech (verbalication) and bodily acts. With other words, deeds (in mind, speech and body) are now "controlled" in an inwardly manner and no more just and outwardly evaluation, in a ways of outwardly comparing appearances but by relaying on mindstates, e.g intention (cetana), not to mix with purpose) for it. While the wordling act merely fixed on the gain of certain fruit (vipāka), the Noble Ones view has turned to the quality of the action (kamma) when deciding what and how to do.
In regard of the virue of a streamwinner there are many views and disputes of which, how and if a streamwinner can break the basic four precepts and missconuct in consuming means which cause heedlessness.
Since the virtue of a Noble person of first degree is based on gained right view, he/she is not able to act strong unskillful deliberated. It might be that faulty acts happen in "affect", but even done he/she does not hidde such a fault and has a natural desire to confess it immediately.
How ever, he/she is in any case incapable to performing acts out of niyata micca ditthi, evil wrong view, and therefore incapable:
Quote from: Commentar to Sn 2.1
- the murder of arahants (the Consummate Ones),
- the shedding of the Buddha's blood,
- causing schism in the Sangha, and
6.pernicious false beliefs (niyata micca ditthi).
In reagard of more detail of the virtue, my person gave recently some words on it in a discussion: Can there be Non-Attachment without Virtue?
In regard of recognition by others (and in the case one seeks for prove by others), is needed to know, that only a "person on integrity (e.g. a Noble One)" can know of anothers persons integrity (MN 110). The Sutta Paṭisalla Sutta: Seclusion contains also explainings here that:
It's through living together that a person's virtue... It's through trading with a person that his purity... It's through adversity that a person's endurance... It's through discussion that a person's discernment may be known, and then only after a long period, not a short period; by one who is attentive, not by one who is inattentive; by one who is discerning, not by one who is not discerning.
My person will end here in regard of the first question.
➨2. Does being a stream-winner in a previous lifetime, mean that one would be reborn into a devout Buddhist family in this lifetime or would definitely be led to the Dhamma eventually?
No, there are certain kinds mentioned and about the "leding", he she would definitly. On how: see answer question 3.
A steam-winner will be born
- mostly 7 more times in the realm of the Devas (sensual world is no hight path is gained) or human world, here:
- reborn in a good family
See AN 9.12 (Bhikkhu Bodhi):
... With the utter destruction of three fetters, this person is a one-seed attainer who, after being reborn once more as a human being, makes an end of suffering.
... With the utter destruction of three fetters, this person is a family-to-family attainer who, after roaming and wandering on among good families two or three times, makes an end of suffering.
...With the utter destruction of three fetters, this person is a seven times-at-most attainer who, after roaming and wandering on among devas and humans seven times at most, makes an end of suffering. ...
➨3. Is the reborn stream-winner's Dhamma eye open immediately at birth, or only after he or she encounters the Dhamma and returns back to the Noble Eightfold Path?
He/She maybe not conscious about having the " Dhamma-eye but like answered to question 4. is not in a strong danger to follow wrong teacher, in an amout that is not in the frame of the conduct and way of thinking of a Noble One.
Becoming aware about the Dhamma is also answered under question 4, which can have four general typs of reminder:
➨4. How is it guaranteed that the reborn stream-winner would not choose another path or another teacher, and drop out of the stream, considering that we do not remember previous lifetimes?
AN 4.191 indicates that one (here a previous monk appearing under Devas), if not reminding him-/herselves ("dies with a muddled mind") either is remembered by
- comming in contact by him-/herself
- a monk with special power
- a Deva
- a "familary" spirit
One is incapable to "fall out" or "follow other Paths", since - like in the 1. question answered - the fetter "doubt" is abounded. Now it might be possible that he/she trains within another religion als long and in so far, the views and practices contain the factors of the noble eightfold path. It's so possible, that if one maintains a "mystic" approach in regard of "God", it could be that one practices as Christian, or better under Christians, till one meets the good Dhamma, for example, or in certain other sects, but will maybe oppose certain things there naturally.
So it is guaranteed by or through his/her previous deeds, the fullfilement of bringing together all pathfactors and the hearing of the good Dhamma with proper attention in advanced.
➨5. Please provide any info from the canon regarding this.
The answers should already countain the sources. One of the best collection of Suttas might be the Studyguiden Into the Stream - A Study Guide on the First Stage of Awakening, by Bhante Thanissaro, which will provide many additional informations and teachings, not only for gifted "Noble-Born's" but also for Dhamma-, Faith- and most suggested for those "with little faith" for now, to not only gain more of it, but also put all means into practice and finish a task so less are capable, bringing behind the most of all burdens to be for ever behind.
Association with people of integrity is a factor for stream-entry.
Listening to the true Dhamma is a factor for stream-entry.
Appropriate attention is a factor for stream-entry.
Practice in accordance with the Dhamma is a factor for stream-entry.
— SN 55.5
May all beings have share of the merits here done with the support and sacrifies of many and may the Devas inform those not having seen or heard yet.
You may find a possible extended or modified answer here, being also invited to comment, discuss or what ever insired: On Being of Noble birth - Stream winner reborn as human
(Note: This is a gift of Dhamma, came into being by goodness received and gratitude and so given by goodness and gratitude, and not meant for commercial purpose and trade in the world, or any wordily gain.)