Legal Question in Family Law in Texas

Child custody can be determined in a divorce or by a Suit Affecting Parent Child Relationship. This is often called a SAPCR.

If you file divorce, custody can be determined pending the final orders by a hearing on temporary orders.

SAPCR suits are usually filed by unmarried parents. However, they are also available to separated couples. The issues are custody, visitation, and child support, just like a divorce.

The short answer to your question is whoever the judge decides. Of course, if one parent files the suit and the the other parent never answers, then the parent who files would win.