I’m not sure that field can be brought into PAM, but it can definitely be brought into field mapping.
The data you need is stored in [SupplierList].[ReorderNumber].
The [SupplierList] table holds information about specific Product<>Supplier relationships, where [SupplierList].[ItemID] is the unique identifier of the product (which will match [Item].[ID] from the table where most product information is stored) and [SupplierList].[SupplierID] is the unique identifier of the supplier (which will match [Supplier].[ID] from the table where general information about the supplier is stored, and should match [Item].[SupplierID] from the table where most product information is stored IF they are the primary supplier).
The best way to proceed will very much depend on how accurate your data is, and whether you always have images for product where there is a valid [ReorderNumber], but if you raise a ticket I’m sure the support guys will be able to advise you.
NB - each of the [ID] fields above is an internal numerical reference in the respective database table, and is NOT a value you can see in RMH or should ever edit.