Park invoices that havent been Goods Receipted

Dear Gurus,

We are looking at a way of parking invoices on our system that havent been GRN'd but want to maintain Goods-Receipt-Based IV button ticked in the PO to ensure that the functionality around this are maintained.

We also want to be able to allocate the PO line items to the Invoice but again if it hasnt been GRN'd MIRO doesnt pick up the PO in question.

I have looked at transaction MIRA but this only Holds an invoice rather than Parking it and we need to be able to allocate a FI Document.

Any help or guidance would be greatly appreciated.

Feel free to ask for additional information.

Regards

John