Legal Question in Family Law in Texas

I'm sorry, but no, you don't have any custody rights to your grandchild. This is a bit of an oversimplification, but basically the only rights Texas laws gives grandparents apply in situations where the parent has essentially abandoned the child with the grandparent for at least six months, in which case the person the child was left with (grandparent or not) would develop standing to sue for custody), or in certain very specific instances where the parent who is the grandparent's child is deceased or otherwise unable to decide whether allow the grandparent access to the grandchild, in which case the grandparent may petition a court for periodic access under very specific circumstances. However, assuming your daughter is competent enough to be capable of making the decision that she wants your grandson to be with this friend of hers rather than with you while she's away, she's the one who gets to make that decision, and there's probably really not much to be done about it.