Peggy was helping Natasha and Tony set up, decorate, etc. She will linger afterwards to assist with the clean up as well.
Molly would be curious about the American holiday and also birthday celebrations are lovely.
Betsy will happily toast the good captain.
MJ hasn't introduced herself to the masses, she almost doesn't want to because it's not exactly her style. She's skulking around, more interested in stealing food and then retreating to a quiet corner.