There are many good answers in the question Would Buddhists help non-Buddhists continuing their attachments?. I'll summarize some of the points here:
Buddhism only teaches that things don't last, not stop doing them. Love people knowing that someday we lose them; use things knowing they break; earn money to survive not out of greed; eat food only to be healthy not because taste good. Even if the girl is attaching to her mother, helping them or not will not make them less attaching anyhow. (ashen25's answer)
Dhammadhatu's answer even cites the suttas:
Buddhism has two levels of teaching: (i) moral, which includes attachment; and (ii) non-attachment (MN 117). The Buddha said his teaching of non-attachment was only for a minority of people (MN 26).
Therefore, a Buddhist would help ordinary people maintain their important social relationships. In fact, this is a duty of a monk (DN 31). The duty of a monk & of a Buddhist is not to "strip" ordinary people of their attachments & identities.
The consensus in there is clear: helping them, not converting them. However, psychologically speaking, I think helping people necessarily requires both parties forming a relationship, or requires the helpers involves/attaches in other people's emotional dramas. Or when they are helping them, they need to have expectations on the outcomes. These are things a Buddhist would like to avoid.
They can simply say "sorry, my goal is not to get attached with relationships. I'm not a suitable person to help you. I hope you get well with your life." Not only this is an acceptable manner, this would also conveniently help the helpees understand the value of non-attachment without the need to teach them anything.
I think the solution is simple: as long as the helpers acknowledge that after the problem has been solved they can detach to it, then it would be fine. However, are there any sources discussing this?