I have had a few days to sit with this and the following is a summary of my thoughts on the matter:
The issue is basically that when we forced the Polish alliance with the Allies back to after Danzig, no one realized that this might interfere with the hardcoded trigger that brings any of the Benalux countries into the Allies when Germany attacks them. This is because the Allies were not at war with Germany when Germany attacked Belgium, and so the trigger did not go off. It simply never occurred to me that such a circumstance might arise, when Germany attacked Poland, and Poland was not in the Allies, otherwise I would have established that by added events.
Again this Alliance is hardcoded into the game system, and it is my fault chiefly that I did not forsee this possibility.
That said there are really two ways that the game can be edited, and I think that the Allies prefer that the war against Belgium be removed entirely. I think I can say this on behalf of everyone, based on our post game discussion. It seems that Germany DOW'ed Belgium in the expectation that Belgium would not join the Allies when it did -- based on playtesting perhaps? That is our preference. We believe this is best for the game in the long run, and since it seems Germany made this decision based on the expetation that Allies would not legally be able to do anything about the early invasion of the Benalux, I think we would extend the offer editing out the war with Belgium, and the Allied war with Germany, until the Polish event fires, and we can go with that.
I think that would be fair, and also good for the game, since we would not want to put the whole future of the German strategic position at stake because of this unforseen circumstance, after so many hours of play bringing us to what otherwise seems like a promising start.
However, this is a German strategic decision so its up to the Axis to decide. But also, if the Axis does decide to continue with the war against Belgium that is fine, but I would also ask that France have its dissent reduced by 5, as it is the case that France on DOW'd Germany in the hope of bringing Belgium into the alliance as it is hardcoded to do when Germany attack Belgium, because Allies were not able to bring Belgium into the Allies diplomatically.