Can R42520 control what lots and quantities are assigned?

We are running JDE 9.2.7.2

We have the following doubts, hope you may help us clear up:

Scenario 1: order creation for 500kg, only 150kg were available. When running R42520 the batch was assigned to the 150kg satisfactorily but the remaining 350kg were left on a line whose status was 982-999. We understood that the line could remain as a back order, so that Customer Service effectively knows the amount of KG that are still left.

Is this possible?

Scenario 2: order creation for 100kg, there was a lot with 11kg and another lot with 1275kg available. When running R42520 the lot of 11kg was assigned and the remaining 89kg from another lot. The 89kg causes an error on the next step, because of the unit of measure. Is there a way to avoid lots being used in this way? For example, when dividing them, they are at least 25kg or an increment we can control?