Tiaa was the wife of Amen. 2 (the wanker king) but didn't receive the title of "God's Wife of Amun" which is often seen as a rejection by Amenhotep 2 of the dynastic importance of women (some also state that Amen 2 was responsible for the erasure of Hatshepsut's name on monuments). According to Der Manuellian, she was his wife though.
There are some who say she may have been a Mitanni princess and daughter of King Artatarma, although there isn't a great amount of evidence supporting this. If it's true, it would have contributed a lot to the safety and stabilityof the area.
She did receive the titles of "God's Wife" and "God's Mother", meaning she was definately the mother of Thut. 4. There is a school of thought, however, that she may have received these titles only after Thut 4 ascended to the throne.
