So, my DFR is acting up again and the fuel is returning to the wrong tank. Last time I disassembled the DRF and cleaned the valves and it worked for a while, but I didn't know where to get new o-rings for the vales, so just reinstalled one with a small chunk missing. Don't know if the damaged o-ring is the problem, but winter seems to be coming ahead of schedule and I'm running out of time.

What I'm thinking of doing is cutting the front tank return line and teeing it into the rear tank return line. I've been using the rear tank only for many, many years. My primary concern is if I'd need, or want a check valve in the rear tank return line to prevent the returning fuel from heading back towards the front through the rear tank return line. I suppose, if any fuel went back up into the reservoir it would just hit the non-functioning valve in the DFR and not be a problem. Any reasons teeing the one return into the other would not work?