You already have a table where each check written is a single record and all advances represent a check that is written?
If so I'd add at least one field to that table to record the number of the related invoice the check is written against. The total amount of all checks with a given invoice number will give you the total to date disbursed against that invoice.
If one check can represent multiple invoices, you'll need a Child table that breaks down each check into 1 record recording the sub amount for each invoice. Then all records of this child table with the same invoice number will give you the desired total.