Creating 2 invoices for 1 PO

I have created a PO with payment terms 30-70, when I generated a purchase invoice and entered the invoice number I have from my supplier, which is for only 30% of the payment, the whole PO is marked complete, which is not the case.
How do I do that? or do I have to create 2 POs?
I have seen in the invoice there is also a breakdown of the payment, but this doesn’t solve the issue that I can’t enter the 2 invoice numbers that I have from the supplier, since there is only 1 field for the supplier invoice number per purchase invoice.