Hi, my name is Tom. ATM I use the FF utility called F4XChange available at the FreeFalcon site:http://www.freefalcon.com/forum/showthread.php/16377-F4XChange-Released/page14
Creator is Khronik.
I already had 2 FF installs installed and stored via F4XChange. This utility manages Falcon registries.
After having my 2nd FF install ready, I installed BMS4.23.
(Did not even deactivate my with F4CXChange activated FreeFalcon install, just installed BMS4.)
No issues on my rig, I see 2 seperate registry entries for FreeFalcon5.55 and BMS4.23.
BUT: I would rate this question WIP since not many FF teammembers have investigated on the issue and I know of one teammate who could not use his last FF ITO2 install which he installed after BMS4.
I assume F4XChange is the safest way to use FreeFalcon and BMS.
That's not proven, only my experience.
Check above link and homepage for additional info.
Or feel free to ask at the BMS site as well.