It sounds like you're taking proactive steps in managing your claims. It's understandable that you want to ensure fair compensation for your lawyer's work. If you decide to remove your lawyer as your POA, they may still be entitled to payment for the work they've already done on your OSA appeal, especially if it's already in progress. However, it's important to clarify with your lawyer whether they will continue to represent you for the OSA appeal even if you remove them as your POA.
If you need further assistance or legal advice, this resource on Dodd-Frank lawyers might provide helpful insights https://federal-lawyer.com/whistleblower-lawyers/dodd-frank/. Best of luck with your claims, and thank you for your service!