I know how to add, subtract or combine one solid body fromanother but can I do the same for parts?

I would like to animate water filling a vessel and thought it mightbe possible that after starting with a full vesel I could thensubtract a hidden volume as this volume moves up. The final resultbeing that it appears that the water is filling up.

Thanking you in anticipation.

CameronSolidworksAssemblies