needing help with a formula change

hell everyone...okay so I'm working with this excel and i would like to make a small change but stumped because I'm not great with excel. I want to change the way it calculates the attending on the left bar of the excel sheet. If you change rsvp to yes it counts it as one but it does not include the party. I would like it to calculate the # in the party as well so i have a more accurate number. please let me know if this makes sense and if its possible

The formula is =SUMIF([RSVP],"Yes",[PARTY])

Also, not a bad spreadsheet. I wish all the other "dumb" users knew so much