Cancelling a parallel subflow

Hello - We are currently working on a workflow where we will have 2 subflows moving at the same time, we'll call them "one" and "two". If either "one" or "two" get voted to a previous step we want to cancel the other. To handle this I thought we could get away with containing them in their own subflow, "one-two",  so when "one-two" closed it would close whatever is left open. This is not the case if "one" gets voted to the previous activity it would close and "one-two" closed but "two" stayed open and I can't vote out of it because "one-two" is not longer active so the activity on "one-two" that holds "two"'s workflow is now closed as well.

I can use methods to get to the other subflows ID I'm just worried about missing something while trying to cancel or close the other activities.  Would someone know if there is an existing method in Aras or a proper way to handle my scenario that I may be unaware of?