tying a specific FinancialItem (work order nternal cost) to a specific InvoiceLine (invoice line item)

I can pull the internal costs for a work order from the FinancialItem endpoint
And I can pull the invoice line items for a specific work order from the InvoiceLine endpoint.

Our system appears to have a 1-to-1 relationship between work order internal costs (FinancialItem) and invoice line items (InvoiceLine). I only looked at 20 or so work orders so that may be misleading.

Is there a way for me to get a specific InvoiceLine record, if it exists, from a specific FinancialItem record?
I didn't see anything the payloads from either endpoint that could do that.