@keith Good suggestions all the way around. In the meantime, you may find it quicker to do your splits in Excel in advance, save as CSV, and then upload transactions already broken down. Up to you…
Also check out this similar request: Auto-calculate interest, principal, and escrows for mortgage payments
Also note that Stessa now supports up to twenty (20) splits in a single action. The previous limit of five (5) child transactions has been retired.