I think you've asked this question several times before. You need to review the PPM for the hedge fund to ascertain whether other funds could be part of the fund's portfolio. You also want pricing reports on the illiquid investment and information on any "side pocket" the fund may have created.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.
Start by pulling the ppm and the account opening documents with this firm. There may be an arbitration clause and a forum selection clause. This would limit your ability to pursue legal action if for instance they were out of state. If there investment policies or procedures stated in the ppm wasn't what took place in practice than you may have a claim. Good luck!