First grandchild

So I'm married to a twin and his bother is also married but he married a girl that had a baby already (not his). So now me and my husband (his brother) are expecting our first child which is the first grandchild and the first great grandchild in his family. So we out to eat with his mom, so his mom was saying "oh she is so excited, she can't wait for her grandchild to get here" So then my sister n law daughter says, "well you already have a grandchild, me" Now apart of me is psst because I feel like I have been discuss as well as my un born child. Keep in mind this girl never call my mother in law grandma at all until I announced I'm pregnant. My question is: Is there Jealousy there with my sister n law and should I say something because I don't want any drama once my baby gets here?