My son got married was blessed with a child , they diveorce and child support was order ,but she got pregnant and have twins and never file for child support will the oldest child will be 18 in a few months now she file for clid support for the twin, he don't mind paying it ,but thinks they shouldn't be able to go back 12 years.She said that the reason was that she could draw more money filing it this way. Oh we live in Texas