What to do -- Custody Issue --"protecting" other people's children

Young daughter just called. Her father doesn't have phone numbers or email addresses of any of the parents from the school. Why is that? Oh, because he's on no email list nor does he have a PTA handbook. Why not?

She wants the phone number for a friend who has never been to my house or his house. I've been planning to invite this child over and I've nurtured a relationship with her mother and grandmother.

I don't want to give the phone number. I don't want this child going to his house, where there is inadequate supervision.

So, I'm stuck withholding a phone number from my daughter.

The phone number thing happens regularly -- the kids call ME for the numbers.

Am I right to do this?