Good morning, I’m new pool owner and just had pool installed. Running it for 2 months and can’t seem to heat spa by itself. From my research online it looks like I am missing a return line from my spa. All my valves are manual , so switching over done by hand. I’m including pictures of setup to try and get advice in how to proceed going forward. From what I determined is that the main pump can pump to either waterfall , spa, 2 keys in back of pool and 2 jets on stairway of pool, and main drain in bottom of pool. The returns are just from main drain and either skimmer. Then I have separate pump with supply and return to spa. What I am thinking of doing is adding a three way valve on return of that separate system and piping into main return with tee , right at main pump and then I will be able to heat the spa by itself but won’t be able to run bubbles and small pump. What do you gentlemen think?