Able to mix South Americans cichlids with shell dwellers?

I have a 60g breeder tank that currently has 2 polar parrots, an electric blue acara and a Severum in it. They’re all pretty small still and I was wondering if it’s safe to add some multies into the tank. My Ph is about 8.2 and my water is pretty hard. I was thinking about adding maybe 8 multies or so and putting some shells in the tank. I have a fine white substrate. If I’m able to add multies, do yall have any tips. If not, what do you think would be good to add to the tank?