Content size is not calculated correctly with cancelled parts

[pascalfree]

Description

If a part is cancelled, the content size to be distributed does not decrease, only when the part is deactivated. This is an issue if a part is changed, i.e. one is cancelled and another one is ordered. Then the content size will be too big.

Suggestions

The content should be assigned to the parts, not to the subscription. That way the content that should be removed with the deactivation of a part can be assigned to the cancelled part.