i see two solutions for your problem:

[ul]
[li]why don´t you use 2x2 voices not placed in the mid but let´s say 25 +/- from the mid and with massive chorus (from my point of view, the chorus broadens the sound quite impressive and to some extend surreal) instead of all four[/li]
[li]or start first with 4 voices and before the transition blend out one voice after another and on the other side blend in one voice after another[/li]
[/ul]