Ceiling Mounts for RM6200 speakers

My living room was pre-wired for and set up with a Bose Lifestyle AV system by the builders. The speakers are attached to Bose UB-20 ceiling mounts, as pictured below

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The Bose AV Media Center has now croaked. Over the last few days, I have researched this matter and come to realize that Bose is a poor investment and that its components are intentionally designed to not play well with others.

I would like to replace the Bose system with a Polk RM6200 speaker system and an AVR that I purchased some years ago. However, the Bose UB-20 speaker mounts for the satellite speakers have a 1/4" bolt for attaching the speakers, while the Polk RM6200 satellite speakers use what appears to be a 10/32" bolt.

I really do not want to try to change the ceiling mounts, as they look great and appear to be very excellently installed. Instead, I would like to find a way to attach the Polk satellite speakers to the Bose UB-20 ceiling mounts.

Is there an adapter bracket that I can buy that will enable the Polk satellite speakers to be attached to the Bose UB-20 ceiling mounts? Or, perhaps a 1/4" to 10/32" thread adapter to effectively narrow the size of the bolt hole in the Polk speakers? Or does anyone have any recommendations for a better way to approach this, preferably other than replacing the ceiling mounts?