Are Return Ducts Beneficial in Bonus Rooms

All,
I've got a question for you. I live in a two story home approximately 2400 Sq ft. with a bonus room above the garage. The heating/cooling equipment is located in the attic. In two weeks, I'm going to have the first and second stories split into separate HVAC zones.
An additional issue I'm facing is the bonus room is either warmer or cooler than the remainder of the house depending on the season. The HVAC tech suggested adding a 12x12 return duct in the bonus room; in addition to a previously existing duct in the upstairs hallway, to help equalize the temperature. I read the return ducts should equal the total size of the heating/cooling ducts in the rooms. So, if a second duct were added in the bonus room, would the existing return duct in the hallway need to be reduced accordingly?
Any information you can provide would be helpful. Secondary resources would also be beneficial.
Regards, Orlanzo
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Orlanzo wrote:

Normally yes.
--
Joseph Meehan

Dia \'s Muire duit
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wrote:

Actually, since you don't post here that much, you don't need your thread name. Your author name will do, in advanced search.

P&M
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