I have 2 daughters 6 and 3 their birthdays are both next month. My 6 year old doesn't have a dad and only has me. My 3 year old does plus all these other relatives from his side. There's no relatives my side.
I like to treat them both equally and spend the same amounts on them to keep it fair. But doing this my eldest always ends up with so much less as my youngest has this whole other family buying for her. Aibu spending a lot more on her to even it out.
Yabu: you should spend the same on both
Yanbu: You should spend more on the eldest to even it out.