Did you start with creating a manual receipt import using Excel then used those fields mappings as the basis for your API calls?  If you can get an Excel import to do exactly what you want then you should be able to replicate this manually in postman through the API, then once that's achieved, build your API call programatically to submit the exact same data?  If you've already worked through these steps and its still not working then you could try Sage Support but you might need Development Partner support - i.e. find a business partner who is a development partner and get them to help?

Hi, thanks for responding. I built some POs / PO Receipts via the UI and then inspected them in the API. I replicated the fields in my calls (and tried many variations!) but the Purchase Order information contained in the POReceipt does not seem to be recognised. The receipt is created/posted and the inventory updates, but there is no link between the POReceipt and the PO

I have seen (older) posts on this in prior iterations of this Sage Community, so perhaps it has never been fixed? (e.g. see https://www5.v1ideas.com/TheSageGroupplc/Sage300ERP/Idea/Detail/41067)