I had a similar problem with a 18' round AG pool. Check with the Manufacturer for Vertical upright supports for your model. Mine were 2 feet high (If memory serves) and were placed behind the upright next to the side wall at the bottom near the bottom sidewall track. You may have to partially disassemble the top rail to gain access to pull the verticals out far enough to install the supports. Mine was done without draining, one vertical at a time.

Good luck. BTDG