Sure, and if you have alternate people, bring them out and they will get different animals to come shop also. I'm not positive with ACCF, but with ACWW three would come, and then you would have to go out and do something, and go back in before any others would come, but they should all come at least one time. Are you all ready for it? I am. I moved all the stuff I want to keep out of the main room, and put all my "sale" stuff out. During the sale go and check the recycle bin at the Civic Center, as a lot of times you will find things you sold in there, and then you can take them out and go sell them to Nook, getting more bells. Have fun.
I haven't expreimented that much with the flea market in accf, but all the posts I've seen, say you can only get a max of 5 villagers visiting you. (possibly less if you have a villager sick or packed up to leave). I've never got more than 5 to visit any one character (I doubt very much if you save & reload you would get any more).
But as said, all 4 of your characters can do the flea market & should each get 5 villagers visiting.
Do check the recyle bin regularly - plus also walk around with a 2nd character after you have completed the flea market with your first: - I've been offered amazing trades (eg Olivia wanted to swop the shark she had previously bought off me for 44k, with the tiger butterfly in my 2nd characters pocket).
Each villager will only buy 3 items, going into another room & returning does not reset the counter as it did in acww.
As villagers won't buy special event furniture you could screen part of your main room off using this sort of furniture rather than clearing the room altogether (the max you can sell is 15 so there is room). Or I screen off with double rows of bugs/fish.