If there was no court order in effect at the time relating to the custody of the children, then the mother had every right to take the children.  If, however, there was a court order so in effect, then she may have violated it and can be held in contempt of court.

Right now the father needs to consult with an attorney in his area.  To best protect his interests, legal proceedings should be initiated so that a court can make a determination as to proper custody arrangements. 

M.D. is correct.  Under the circumstances cited, unless there is a court order, then the mother had the right to take the kids.  Each parent is a parent and has the right to possession of the children until the Court issues an order otherwise.  Since she left without filing for divorce, you should not only consult with a local attorney, consult with one sooner rather than later.  Texas jurisdiction over children/divorce is limited to the county where at least one party has resided for the past 90 days for the Divorce action.  Child custody actions are appropriate where the kids live or have lived for the previous six months, if any such location exists.  The longer you wait, the more likely she is to establish domicile somewhere else.

If you are in Collin or Dallas County give me a call.  You can also find more information on my web site at www.planoattorney.net

Roy L. Reeves, Esq.

Reeves Law Firm, P.C.

www.planoattorney.net