using my son's name

my husband and I lost our son almost 4 Years ago. his middle is Felix which is the same as my husband and my husband's grandfather. last week my husbands grandfather passed away and his sister wants her son's (due Oct 14th) middle name to be Felix. my mother in law asked my husband and I if she could use Felix as her babies middle name and I immediately broke down and said no. am I wrong? should I be ok with her wanting to use the name? I don't know what to do.