Once the Balas are gone, you still may need to decide between keeping the Angels or Tetras in this tank (so either a new tank or another fish to sell/re-home), as adult Angels snack on Neon Tetras. What Tetras have you got?
The Angels will need 18" of water depth (so excluding the gravel/sand and the air space above the water) to prevented stunted growth. Does your 37g fulfill that requirement?