Hi Pippa,
You can only use distribution for priamry cost element. The costs are transferred to the receivers
using the original cost element, so they are transferred to the primary cost elements of the receiver.
Secondary cost elements remain on the sender.
The assesment(T-code:KSU5）allocates primary as well as secondary costs. The information on the original priamry cost elements for the sender is lost because the costs are allocated using an assesmaent cost elenent(category 42). You can use more than one assesment cost element for differentiation purpose.
so for your issue, I think you can try to use KSU5 (assesment).
Best regards,
Ronghua Fan