Sage Importing of Purchase Orders from another ERP system

Hi All,  I'm new to this so apologies if this has already been asked.    We have been using Sage50 for years, but always entered purchase invoices direct via batch invoice, because we use a 3rd party ERP system for purchase ordering and GRN.  Currently there is no plan to move away from the ERP system.  So my actual questions are, if I want to import purchase orders to sage via CSV file would I need to import PO's and then receipts or could I import just receipted PO's?  and would sage cope with multiple receipts across several weeks on the same PO (if I was just importing receipted PO's)