Name Dilemma...Please help!!!

My husband's sister passed away last year. When I found out I was pregnant, I agreed to give the baby her name as a middle name. I am having a girl. However, now his family is acting like she'll be a replacement for his sister and already comparing the baby to the sister. Even to the point that they want to also give the baby the sisters nickname.

I understand they are still grieving but I no longer feel comfortable and don't want to name my baby after his sister. I'm struggling to find a way to tell my husband. This is also my first girl after having 3 boys. All suggestions welcome.