Using Special Procurement Key for alternate supplying plant

Hi All,

I am using special procurement key this way:

1) Plant A - Line 1 - Supply from Plant A for raw material i

2) Plant A - Line 2 - Supply from Plant C for raw material i (using special procurement key)

After first creation of the plan order at line 2, the dependent demand is at the correct plant. However, when a change is made (e.g. quantity), the dependent demand went back to Plant A. This can be fixed when planned order Imodel is reset.

As a workaround, what else can be done to get a quick view of the effect of changes in planned order on the raw materials at individual plant?