Vendor-SKU-Variant relationship - best practices question

I have read a lot of threads about UOM and variants but haven’t been able to answer this question for myself. Maybe because it’s midnight but I just can’t get this to work. The scenario:

I buy a chemical (lot-tracked) which I stock and consume in grams. I have 2 suppliers and each sells it in 2 different size bottles: 2kg and 10kg. Prices for each size are different and each has it’s own vendor item number.

I have set it up this way:

Base unit=g. My purchase units have to be Kg since there are multiple sizes of container.

The Item Card for the chemical has 2 variants based on the volume of the container, 2K and 10K. I had to add new units of measure to the item card for each variant so that I could order the containers in the vendor’s handling unit (each.) Whether I want to buy 2 kg or 10 kg, my order quantity still has to be 1, right?

This all works pretty well. When I create a PO for Vendor/Item/Variant, the direct costs all come up correctly. Yay.

Problem: I also need the vendor’s item # for each item/variant to come onto the PO line. The only means I can find to do this is to create a SKU card. But there seems to be a 1:1 correlation between SKUs and variants. I cannot get NAV to generate a SKU card for different vendors and the same variant code.

I am missing a critical bit of understanding here. I suppose I could have the purchaser fill the vendor item number in manually but that stinks. It seems like this should work.

Teach me the ways, great shamans.

What about using Item Cross-References?