how to add cuts for transparency?

So I'm trying to make a sink with 'crystal' knobs by taking the handles used on the parenthood dresser and putting them onto a basegame sink. I know that the knobs have to be in a different cut to make them the only part of the mesh that is transparent, but I'm unsure of how to make sims4studio recognise that there is an aditional cut to the mesh, i.e. the original sink had 2 cuts, but the knobs now add a 3rd cut with previously did not exist. Is there a tutorial out there explaining how to do this? Or should I go about making the sink in an entirely different way?