Subrogation versus other drivers insurance offer

My 1998 Mazda was hit from the rear and totalled. Due to circumstance, was unable to get the name of the other drivers insurance company at time of wreck. My insurance company USAA asked to subrogate the claim and made offer on totalled car. They are working a andquot;finalandquot; offer now. But, 2 days ago found the other drivers insurance company is GEICO. GIECO is now appraising the vehicle. My desire is that I get the most in order to replace the vehicle (I was 0% at fault). GEICO says 2-3 days then they should have offer. I really want to get USAA to wait out for GEICO offer. What advise can you give me? The amount USAA offered is approx $3500. I can't find any equavalent on internet sites without 30,000 - 75,000 more miles than mine had, and then prices are in the $4000 plus range.