Telling Grandparents about Pregnancy

Hi Sisters,
Hubby and I are planning our first cherub. I want to announce our pregnancy in an over the top way because this has been a long time coming.
On my side, it's first time grandparents/great grandparents/uncles so there'll be excitement there, but my in laws are already grandparents. Is it still ok to say "you're going to be a grandma/grandpa" to my in laws since technically they already are? I just feel like they're going to sit there and say "but we already are!"
Any suggestions on cute ways to announce to family will be appreciated!
Thanks ladies.