Distribution key in COPA

Hello Experts,

In COPA planning framework we have created a planning for sales volume for customer-product combinations on quarterly basis. We use a distribution key to distribute the quantities equally towards months. So employees enter a sales volume per quarter in one planning level and in another planning level they can call up the figures per month. So far this works perfectly.

However, before the employees enter planning data in the planning on quarterly basis, they want to copy actual (invoiced) data to the plan for reference purposes. This way values from the actual line items are added up and appear in the columns for each quarter. The employees should then overwrite this data with planned figures.

And now it comes.....if in jan 6 pieces are invoiced and in feb 9 pieces, these are added up to 15 for the 1st quarter. When copying to the plan, 15 pieces appear for the 1st quarter. When the employee then overwrites this data with plan data (pieces he expects to sell), for ex. 30 pieces, this should be distributed according to the distribution key (10 pieces each month when euqally distributed).

But what happens, the 30 pieces are now distributed according to the proportion of the actual data (so 12 in january and 18 in february and 0 in march) that is copied inot the plan instead of the equal distribution of the distribution key.

How should I prevent that the plan data is distributed according to the proportion of the actual data (which was copied into the plan) instead of the distribution key?

Hope someone knows the answer.

Greetings,

Stephan