Can I reduce static pressure in one room by adding a vent to an adjoining room?
Yes, adding a transfer grille or jump duct will be the easiest and most effective solution. It can be done in a way to minimize transfer of sound between rooms (see links below). Adding a return to the master bedroom doesn't guarantee that the supply/return to the master bedroom will become balanced—the resulting pressure may still be positive or even negative with respect to the rest of the house.



http://www.buildingscience.com/documents/information-sheets/information-sheet-transfer-grilles-and-ducts/

https://basc.pnnl.gov/resource-guides/transfer-grilles