I've been thinking about this quite a lot, and there are a few unavoidable problems.
I think you could play WiTE2 with enhanced TB but keep to the scheduled changes till July 43. In theory the German player could then mirror any transfers from July 43 in both games (any differences in the OOB are at the sub-divisional scale). If you play both with historical transfers you avoid this but that perhaps removes the incentive for the Axis side - not least to test out Hitler's brief idea of concentrating on the Western Allies (which meant he weakened the Soviet front at a critical stage but didn't really do the extent that might have made a difference).
The core problems are that:
a) Soviet gains in WiTW come off the EF box system, so if the axis player decided to send more west than historical because they were doing better in the East this can't be reflected (or in other words you might in WiTE2 still be defending central Poland and in WiTW the Soviets take Berlin);
b) Allied gains in WiTE2 come off the TB system. Now most of this is chrome but the fall of Frankfurt is critical. It will usually leave the Axis side with one functioning NSS and at that point their economy collapses. So again, you could be holding securely along the Rhine in WiTW while WiTE2 awards Frankfurt to the Allies.
It is, to put it mildly, an intriguing idea.
The alternative route of adding the Allies to WiTE2 is vastly more complex and hits a couple of conceptual aspects of the game system. In part you'd have to treat the Allies as sharing pools with the Soviets and no-one knows how multiple, dispersed clusters of NSS would work.
Lets Brainstorm for a bit
a) I don't know if TB force requirements can be tweaked by Scenario Editor but worse case scenario I think we can add additional dummy units to fill soviet TB in WITW after 1943 July to rebalance force changes in mirror game. It will not be ideal solution but as WITE2 game progress these dummy units can be removed temporarily to reflect soviet advance in WITE2 .
b)the opposite is also possible I guess to fill WE TB in WITE2 with dummy units and to remove them to simulate allied advance as closely as possible.
If we cancel all historical units transfer I think it might be possible. It is for sure a what if scenario/system but I am very curious in testing one of my alternative options for west front. That is to cancel/scale down Atlantic wall and instead focus on West wall and an interim wall from Dutch to swiss border. And a delaying action till September/November.
This might free more panzer and infantry units to East front for some more favorable defense line in December 1944 which might allow a Gross Ardennes counter strike in 1944 winter to push for a more reasonable ceasefire negotiations.
Obviously above scenario requires Human opponents as AI can never handle it.
By all means I don't find feasible a combined map game of both fronts. But I think in future Developers might come up with and official version of above concept.
I mean one game 2 separate maps and integrated unit transfer between 2 games. Played completely separately with front lines and other information updated automatically. this might resolve many remedies of game engine.
"Unless a nation's life faces peril, war is murder."
"Sovereignty is not given, it is taken."
"After having lost their lives on this land they have become our sons as well."