Develop a report issue, extract data from OKL and AR using AR invoice number

I’m developing a report to get all contracts (Booked and terminated), rents (From OKL Streams) with its due dates. And the associated AR invoices with its status if it have a remaining amounts.

My issue here I can’t find an invoice number or ID any OKL Stream table to have a connection between OKL and AR Invoices by invoice ID or Number. Now i can connect the OKL with AR by the Rent date and the associated AR invoice date but this is not accurate.

Can you please help me, which OKL table i can get an Invoice Id or Number to connect it with AR invoice number from AR tables?