My boyfriend recently found out through dna testing a child he claimed for two and half years wasn't his. However, after the child was born they decided to get married, he also signed the birth certificate under the assumption he was the father. Now she's telling him he still has to pay. Right now there is a divorce and child support order in the process. I don't believe her due to the fact this woman is a systematic liar and trouble maker, just in case though I'd ask is this legal in the state of Kentucky.

If he signed the birth certificate especially if he married her within a year of giving birth he is the legal father.

Usually, one can only challenge paternity within a set period. So, as the legal father he would be required to pay support.

I would suggest he consult an attorney.

Yes, unless and/or until he goes though court to challenge the paternity ( even if he can, he may have waited too long) ** also if it can be proved he knew he was not the father and still signed, that if fraud and is a crime also, since it denied the real bio father rights.

But he needs a family law attorney ASAP and he will need to challenge paternity in court

Also some courts even if you are just the step father if you were doing all the roles as the father for the entire life of the child, may be held liable for child support at times.

So yes a very good attorney.