Mercs cheat, u should allow mercing during hunts, like only going to clubs halfway thru last bar thats just cheating
If the club doesn't want merc them they can close the club doors. Mercs are valuable to clubs that have trouble with parties.
The solution to people joining halfway through last bar to get eggs is to have the number of eggs that drop correlate to the number of times you hit the party, more hits=more eggs, not to eliminate mercs