It appears that the Supplier Price list is not site specific…That’s great.
However somewhere along the line the primary supplier value has changed from the erp.PartXRefVend.PurchaseDefault field (or at least from posts mentioning Primary Supplier) to the erp.PartPlant.VendorNum.
This means that although you can be in any site to create a supplier price list. You have to be in a specific site to set the Primary vendor…So if you want all sites to have same vendor for that part you have to login and out of each site and update the supplier price list…I know you could create an update-able dashboard or a BPM, but should you need to?
This might just be an unfortunate consequence of change and it might have been resolved in later versions (only on 10…600 here and still not live)