Distribute Items by Diffs in purchase Order

Hi,

Here is the situation:

I create an item with 10 item child based on the diffs associated to the parent, 5 coulors and 2 sizes.

I create a PO and add the item parent to the PO.

Now I want to ditribute the child item by diffs and therefore define the quantities for each child item.

I select diff1 (size) and on the screen distdiff I see all existing sizes availables in ORMS.

Is there a way to view onlky the diffs used on the child item creation, meaning the 2 sizes only?

I can use regroup of diffs that will reduce the sizes... but it will never only be the sizes i use for this specific item...