Hi guys! So my issue is my second floor upstairs is always hotter in summer and colder in winter than the main floor and basement. I know that's typical but there's always room for improvement right? The main issue is a poorly designed system because my furnace is in basement and any warm air has to get pushed (see photos), all the up from basement and main floor to attic and in attic there's a box that has all the upstairs flex ducts branching off of it. Registers are the round type in the ceilings and returns are at top of the walls, 1 in each room except for bathroom. Back to the main problem, the air flow is so weak on that floor and none of the returns are drawing in. Can't even hold a single square of toilet paper to the vent! I did an experiment and went to the main floor that has strong flow, I partly covered half of a couple return vents to see if the upstairs returns would draw in any better and they DID! So obviously I have an imbalance in my system. Would leaving this operating this way increase the supply amount upstairs? The supply air is so weak! So if Them upstairs returns actually functioned better would it increase air flow through the supplies?