Re: DNA and Disestablishment of Paternity
If you signed papers accepting paternity, (for all of the children) I don't think at this late date you can request dna testing (except maybe for your own information) You are the "father" according to the law, to all of the children you signed paternity for.
You can always request custody.
I hope no matter what happens you treat them all as your own flesh and blood. That's what they've grown to believe because of your own actions.
Unless a source is cited, anything posted here by me is only my opinion, and is not meant as legal advice.