According to my knowledge, to become a bodhisattvas, the person should obtain due certainty of being a bodhisattvas from a Buddha with the effect of Karma. We could identify this fact by considering the story behind Maithree bodhisattvas.
There's a nice paper on the topic, called "Why the Buddha Never Uttered a Word" by Mario D’Amato - you can find it on Academia website.
You'd do best to read it all, although you may certainly prefer to skip to a section titled "Mindful Buddha versus Mindless Buddha".
There Mario cites some other work that says:
... Dunne goes on to ...