I am completely confused in this subject:

My husband divorced his now ex-wife 3 years ago. Since she has fallen on 'hard times' she has decided now to peruse child support from my husband. We know for a fact that her eldest child is not his biological child. She was preg when they first got together but he signed the birth certified, thinking they would be together forever. But it was found out after the divorce was finalized that she has cheated all the way through there 5 year marriage and now highly questions the birth of his son.

He wants to do a paternity test to see if the second is his child. If neither child is from him, is he able to withdraw his name from there birth certificates?

I can not blame him for not wanting to pay for 'someone elses childern'.