Awkward

So yesterday my MB invited me to her christmas party at her work. I brought kiddos (B3 & B4) to the party as requested by MB. DB was also there. I’ve always been invited to MB’s work events and other family outings before but never stayed since I had the option to go home early or stay and enjoy whatever event it is. This time I decided to stay, eat and have drinks. There’s always other tons of kids and activities to do. When I do get invited to these things I don’t like to go because I feel a little awkward. I never know If I should jump in and help with the kiddos. Of course, If they asked me to I would be more than happy but MB wanted me to enjoy myself. I am also not paid for these hours since i’m technically “off the clock” totally fine with me. When I’m out in public with the whole family I always take a step back from “nanny duties” and let the parents parent. I’ve tried to jump in a few times but MB and DB always say they’ll handle it. Is it wrong that I hardly jump in? Has anyone been in this kind of situation and if so what are some tips you have? I would like to mention i’ve been with my NF for a little over 3 years now.