Understanding how to use spa with freeze protection on

We are living in a new home that has a system where the pool and spa are connected to the same filter ump. Freeze protection is activated n both due to freezing to subfreezing temps. QUESTION: HOW DO WE GET TO USE THE IN GROUND SPA IN THESE CONDITIONS?

We have the RS4 Aqualink System.
When I push the spa button, the screen says "press enter to override freeze protection or abort" IF I DO THIS, WILL POOL LOSE FREEZE PROTECTION WHILE USING THE SPA? HOW DO WE GET FREEZE PROTECTION BACK ON TO BOTH POOL AND SPA when we are done using the spa at 104degrees

IS IT OK TO USE INGROUND SPA DURING WINTER MONTHS? IS KEEPING THE FILTER ON ALL THE TIME AND THE SPA HEATER SET TO SOMEWHERE BETWEEN 50-60 (IF POSSIBLE) WHEN WE ARE NOT HEATING IT TO USE THE WAY TO GO? DO YOU HAVE ANY IDEA IF THIS IS REALLY EXPENSIVE?

We are pool novices. It is unusually cold in PA right now. Also we really want to be able to use the spa in the winter because one of us has serious back and muscle problems.

ANY HELP YOU CAN OFFER WILL BE GREATLY APPRECIATED AND USED! THANK YOU IN ADVANCE

I have been told by Sylvan that there is a relatively simple way to separate the two systems by adding some sort of valve....?