So happy to have found this quick way of letting sims dine with different plates to one another. The decorative plate sits just a tad bit higher than the default plate, hiding it. Not the wittiest of solutions, but it seems to do what I wanted.
Was gonna go with making the default plate invisible, but that would necessitate having the deco plates out. Not to mention there'd be floating food if they decide not to eat at the table.
Edit. Even better, I found a quick way to also hide the plates so they're not on the table constantly. This is something I've wanted for years.
Meant to ask before, but are you planning on sharing this? It looks cool.