Yes, all are on the same water system.
The return from the 120 goes through my 2 older refugia on the way to the sump, and the 90 return goes through the two new refugia on the way to the same sump. I have 2 Iwaki 30 RLXT pumps in series that pump the water to a T that sends some water to each tank. The skimmer is on the sump, as is a cannister filter with carbon in it.
The new Reef Filler arrived, and is now pumping away from a new 88 gallon limewater reservoir. The existing dual head 30 gpd model automatically changes out 3-5 gallons per day from another 88 gallon reservoir. And the RO/DI is filling a third 88 gallon reservoir. Each of these reservoirs consists of two 44 gallon Brute trash cans hooked together at the bottom with bulkhead connectors and pipe.