I think your owners corporation has to be very, very careful here if only because, regardless of what agreements they make with this owner, they (including you) will be responsible for whatever occurs on common property.
There is no mention of the number of people likely to be involved but you can assume it will be substantial. How are they going to get out of the garage in the event of an emergency. Will there be security? Will there be alcohol involved? Presumably if there are disco lights there will be music? How loud will it be?
I hate to be a party-pooper but your neighbours would have to be nuts to agree to this, especially at such short notice. The potential for disaster is too great and you’ll be the ones who cop it if anything goes seriously wrong.
It’s a big thumbs down from me.
Oh, and they would have to get the permission of every garage owner whose access will be restricted, regardless of what the majority of owners think.