Mass Additions - Split into non-equal amounts?

Hi All-

Fairly regularly, we'll get one invoice that applies to several assets, each coming in at a different cost. The invoice comes through as one mass addition line, but we want to split it into say, 5 lines and assign each line its own respective cost. I can go into the addition and under Asset Details, change the number of units to 5, but when I hit Split, it divides the cost equally among the five new lines. We'd like to be able to split a mass addition line but assign specific costs to each. Is there a straightforward way of