Well... Hello! I have a question about Polyphone.

I'm making a joke soundfont using the "oof" sound from Roblox. The problem is that using one instrument does not sound very good. So, I use a Timbres of Heaven soundfont for the instruments. Anyways, this is my question: I don't know if is possible, but... ¿Can i replace every audio on all the instruments selected.? Because, well, i don't want to do a lot of job. I'll hear your answers, see ya!
(Edit: in Internet there's a lot of soundfonts that use the "oof" sound. But this would help me to create other joke soundfonts. anyways, bye)