Reused name??

I need some opinions// advice. My husbands mom has said on multiple occasions that “his first daughter has to be named after his sister.” Little backstory, his sister was still born & this was a few years before he was even born. That being said he doesn’t have a huge emotional connection to his sister. I feel bad but I absolutely do NOT want to reuse the name. In a way I feel it’s like trying to replace his sister with our baby. Advice PLEASE. what do I say to his mom. What do I say to him. I’m at a loss. I don’t want to upset anyone