Birthday party help

So my husband and I just brought our first house earlier this year. All our kids were born in December before Christmas. We have 3, a 4yo and twins that will be 1. I want to have a small family birthday party in December for all the kids, (aunts, uncles, grandparents, and cousins) I don't want people to feel pressured into getting all 3 kids a gift, so when I invite, how would I word that?