How to explain to family without being dramatic?

Hello good people! I'm wondering hiw anyone you have explained/discussed your choice of poly to extended family? My mom knows and loves both my partners, thuer family knows and accepts us as we are, it's truly beautiful. However, in March I'm going to visit extended family (maternal grandfather, aunts/uncles, cousins). I'm bringing my non-married to partner with me, my wife hates traveling, and I hate to go alone. My grandfather JUST came to terms with me being gay(I've been fully out for nearly 20 years). I'm not showing up and shoving it in thier faces cause that's wierd haha. But 1 of my aunts knows and doesn't necessarily agree with the life style and im worried she'll bring it up. We don't really do PDA to be honest, and again I'm not going just to show off my partner(though they totally deserve it). I just want to go and celebrate my grandpa making it to 80 and hang out with cousins i havent seen for like 5 years haha. Just looking for advice on how to handle that without crashing out haha.

P.s. if you are my partner and reading this, love you