You can transfer Chase UR points to British Airways, then book domestic AA flights through them. From NYC, PHL and BWI, it is 15k roundtrip to Miami, per person. So you'd need just 60k Chase UR points to get everyone down to Miami.

Check the AA website for availability at the Saaver level (nothing from PHL for Thanksgiving week and after, but some out of EWR, and all into MIA, not FLL), then create a BA account, transfer the points, and go through their website to book the tickets.