It is questionable as to whether the copyright is legitimate for any of the works.
No. It may be questionable as to whether whoever is suing you owns the copyrights now, but there is none as to whether the copyrights themselves are legitimate.

Copyright automatically attaches as soon as something is fixed into tangible form. When the author wrote it down, it was automatically copyrighted. You'll want to give Copyright.gov a thorough reading.


I'm wondering whether anyone could offer a tip it would be much appreciated.
Yes. Get an attorney, because you are in for a fight.