I have a similar situation, although I haven't shared the name yet. This baby is going to be named (either first or middle, leaning towards middle) after my father, Sydney, who passed away just a couple of weeks after we bought DD home from hospital. It's a traditional family name through his family and there must be at least 8 or so Sydney's in just a few generations.
Where it's similar is that I'm happy to use it for a girl, as it's also a unisex name, even though it's strictly had male-only use as the family name.
Your family will carry bias towards a certain gender for the name simply because that's what they're used to, but I know Addison's both male and female and think it's a beautiful female name! I don't think anyone she grows up with will even think she has a male name, to be honest!