Originally Posted by
XPac
At the time you could argue T'Challa concealing what was going on from Shuri was an act of treason I suppose. Certainly after Infinity a lot of people weren't happy with him.
But after the time jump Shuri and what little we see left of Wakanda seem okay with T'Challa. So I think by that point he told them everything (no reason to keep anything a secret as far as I can tell) and everyone seemed cool with him.
I think more than anything it was just a matter of him being honest with them, as I suspect Shuri and Wakanda would have supported whatever decision he had made, like they did in AvX, if they truelly understood what was going on.