"They both had at home paternity tests done and both came back negative" - you mean, both possible fathers tested negative?
Rather than going to court, trying to get court orders for multiple paternity tests, etc., why not get bona fide paternity tests from a court-approved facility and see what the results are? Start with the declared father, and if it's not him move on to the new boyfriend. If they both test negative again, start thinking about who else might be the father.

