I wore a shirt that said “from Fur Mama to Baby Mama” and my husband wore the dad version at my sister’s annual 4th of July party in 2022
Was my daughters first birthday and we all went to the zoo for her birthday legit the moment we arrived I just blurted I was pregnant. Everyone thought I was joking. Had to prove with a pregnancy test when we got home 😂
A T-shirt on your little one to say "big brother/sister" or a pic of them holding your scan x
A phone call
You could get a shirt for your first child to wear saying 'Big brother/sister' and have them wear it to a family gathering.