So Kamuii/Avatar is suspected to be taken to Nohr as an infant. And that man shot by a ton of arrows in that one trailer followed by Garon taking you, he's generally accepted to be the Avatar's dad, correct.
If that's the accepted theory (I accept it as well) then that means he(the father) was killed that night you were taken to Hoshiido. But... You have younger siblings.
I mean if the Avatar was like 1 or 2 when taken then that would excuse Takumi. But Sakura looks much younger then you, probably 4-5 years at best. The father had to have been around to have had them too (unless mom remarried).
My point is, if that man is really the dad of the Avatar, then how old would the Avatar have to be when he gets taken in order for Takumi and Sakura to be possible..?
I don't know this just popped into mind and I thought it was weird.