Re: Can She Take Them Back
Since you are married, you both have equal rights. In this case possession is 9/10 of the law... As long as you have them, you control her access to them. (And I might think about limiting her access to them to your home, especially if you think she might take off with them and change her mind). However, if she goes to their school/daycare/other place where you are not around, she could potentially take them and keep them from you.
Your best bet is to get a court order. If mom is in an agreeable mood at the moment, you could write up the agreement and submit it to the judge for his signature. You might want to wait until after that is submitted to bring up child support so as not to scare mom off. Depending on your state, you can get custody orders even if you do not have a finalized divorce.