We've been using Marriott-family hotels in "XX" city for a number of years in this forum for a # of years. Most folk realize after a quick perusal of a family thread that it's really asking about different properties within a particular city. Even some of the SPG folk said it didn't take long to figure it out. It's also been discussed in this thread, so if someone reads this thread they'll know what is meant.
I'll add a wiki to the Marriott-family hotels in "XX" cities that also describes it. I've got faith in my fellow FTers that most will understand what it is. Ironically when I think Marriott-affiliated it makes me think as compared to IHG, Hilton, etc, within a city. I automatically assume that in the Marriott forum that the properties being discussed are Marriott properties so affiliated doesn't really make much sense to me.
Actually, in adding the wiki to the family threads, I've discovered a slight bug which I'm reporting to the tech forum. If there's no wiki, the wiki icon will show up after one's listed in the thread title. If a wiki is added to a thread that has the review icon already displayed in the thread title, after the wiki is added, both the wiki & review icons disappear. I think that happened a few years ago after one of IB's software changes.