With the parallel processing if only one from eighter team approves the change it hits 100%, so your correct the question would be who to handle the outcome.
I think the best approach is to create one team for the approvers, but hat responds differently than i would think it does.
When i create the request it's assignd to Team A (via Process Cap), the authorization kickes in after the change date has been set.
So in BP i re-assign the request to the Infra Team and the authorisation thereafter.
looking at the tasks, thoose are assigned to Team A rather that the infra Team, i don't understand that bit.