variables for the functions ,eating/cleaning
if you look well tables are just empty squares isometric
the characters never touch the top of the tables, objects appears on the table when someone brings foods.
so thats easy
for the layers i have a simple idea
for example you want 1 character who can turn around the table, this is the trick
when the character is BEHIND the table he is on layer 1
when he move on FRONT of the table he switch to layer 3
ALL the items, foods/drinks etc are ALLWAYS on LAYER 2
characters just switch from layer 1 to 3 and gives you the illusion of volume