Def Hp and atk leads and weapons

Can anyone confirm how the leader skills and weapons work together? For example if you have 6 star Carl 40% Hp and 40% def for all melee. Then you put all melee characters with him with weapons saying 30% def and 30% Hp. Does it give those characters 70% def and 70% Hp or does it default to the highest being 40% in this case?
If I could get a fact answer please not someone’s opinion thanks.

The bonuses stack.

Yes, they do indeed stack as per the previous answers in this thread.


Verified by the combat devs in the aforementioned thread.