Second, William Bell did not exist from the Bluverse, he died early on in life like the Wm Bell from the Redverse of seasons 1-3 did. But Wm Bell from the Redverse lived and collaborated with Walternate.
I like the first one the best. The second I came up as a contingent idea to explain the possibility in the history of S4 that the cortexiphan trials actually occurred in the Redverse. But we can get around Peter and Olivia meeting in the tulip field another way and that leads up to her killing her step-father.