for future note, (also for all MCB) when you have a roof leak just cover all you vets and pipes, unless it is an exaust for furnace/waterheater/chimney the tarp itself will let some air pass. so in a pinch get the tarp up and just cover the area. you dont need to cut the tarp, also the tarp will move some and will not be a perfect seal against any vent stacks or roof vents.
I am not a roofer by trade, but i am in Architecture and was educated to become an architect. sorry didnt see this sooner, i was out of town for the weekend. best of luck with the repair/cleanup.
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