What are my son's legal rights as a father?

My daughter-in-law went to visit her family in Oklahoma 2 months before my son came back from Iraq. She took their child with her. Then two weeks before he was due to return, she told him she wasn't coming back and wanted a divorce. My son has started divorce proceedings. She has told him that he can go to her to visit his daughter but he can't take her anywhere because she's just one year old. My son is here in Texas, she changed her address to Oklahoma two months ago.