How to split an invoice for remibursements.

We track invoices from projects against multiple funding sources or grants. Sometimes a single invoice will need to be split between two or more of the grants. I am thinking of tracking the invoices with a single sheet mimicking our general ledger and tracking the grants on separate sheets or a single separate sheet. Then when an invoice needs to be split, using duplicate entries in the GL sheet for the invoice changing the amount of each entry to correspond to the amount that will be associated with each respective grant.

Anyone have a better idea?

My hope is then to have the document builder produce our monthly listing of invoices for each grant reimbursement. I've only been using Smartsheet for two days so I have a long way to go.