Chris, definitely requires a custom solution, I think there are several issues you might run into with batches, in eWM for AFS batches are different then regular batches so what you can do in ECC might not translate in eWM easily. Having said that I think the biggest issue here is that if you distribute the IBD from ECC then the batch is going to be present and the expectation is that you will receive against it. It might be easier and cleaner to use a PPF that performs a cbatch change that way your IBD is closed correctly and also the inventory in eWM matches what is in ECC.
Later.....