A/C Question..

[double bogey]

Get an a/c guy to measure the airflow to all the rooms the system serves. Determine if you have enough volume to do all areas served.
If so determine what is needed to close ducts, and open others to get needed air to all rooms. You cannot do this closing dampers on registers, you need dampers at wyes and sometimes at the plenum.

A properly designed and balanced duct system is the most important part of any a/c system.

[tigerscowboy]

Master is typically the most humid air in the house. Add a R/A at the master bedroom ceiling, right outside the bathroom doorway. Then re-balance the house based on lifestyle.

Idea is to balance the supply as well as the returns. This is a std design on our houses.