Can you tell me what you have for hyd from the pump to the reservoir?
If you have a loader, it may have a PB outlet.
What is your goal? Add more hydraulics, such as remotes at the rear.
If all you have now is 3pt, then the flow is from the pump to the 3pt, then reservoir.
If you have a loader the flow is probably from the pump to the FEL valve then to the 3pt , then to reservoir.
You have an open center hyd system, so all valves should be in series.