Put the twins up for together adoption since mom tried to kill them.
Sometimes these women change their minds. This is why we have Crisis Pregnancy Centers. To help women through this not help them kill the baby.
Leave them be. The parents now realize what a horrible thing they had agreed to do, and are grateful the aboriton did not go off as planned, and happy to be able to parent the twins. It's likely they will be excellent voices for the unborn for the rest of their lives. Converts are the best!