OK so basically if you want the character to hold something and that the thing moves automaticly with the animations it is a prop - there are some props included in the episode - and we can’t create our own props.
the command @add - will automatically add the selected prop to the character
@add PROPS_NAME to CHARACTER
and to remove it from character
@remove PROPS_NAME from CHARACTER
While overlays are independent “objects” which do not automatically move with the character animations - so if you want champagne to be on table instead of in character hands than for this you will use overlay.
So if you want the character to make toas and then put glass on table
you first add the prop,
make him the animation with prop
remove the prop
and let the overlay appear on table.
I hope it make sense if not I can make you an example