How to get the plan distribution orders for the configured customised items when simulate orders (Enterprise planning engine) is run in B50c? (ofcourse when standard inventory is available)

Generally system will generate plan distribution orders when derived from item is linked with respective standard item (irrespective of default supply source in the item plannig data)

But in case of configured customized items the derived from link is always filled with the generic item code!!

We tried with changing default supply source in the item planning data of customized item as distribution. But this has not generated any plan distribution orders.

How to get the plan distribution orders without filling derived from link? why system doesnt generate the plan distribution orders even when the default supply source is distribution and standard inventory is available (& when Customized inventory is ZERO)