Niece's Birthday vs. Daughter's Birthday – How to RSVP?​

I just got an evite for my niece's 1st birthday party, and it's on the same day as my daughter's actual birthday. My daughter is turning 7, and we usually make her birthday all about her – doing her favorite activities, having her favorite meal, baking her a cake, and giving her presents. I’m torn because my daughter might want to see her family and cousins, but I know she’ll be upset if the party, cake, and presents aren’t for her. Plus, my relationship with my brother and his wife is complicated. They blocked me on social media earlier this year after I told our grandma they called our mother "toxic" (which I didn’t say). I want to ask my daughter what she wants to do, but I’m not sure she’s ready for the emotional impact. What should I do? RSVP yes and risk my daughter feeling left out, or RSVP no and risk straining my relationship with my brother even more? #BirthdayDilemma #FamilyRelationships #Sisterhood #ParentingDecisions #EmotionalWellbeing #RomanticRelationships