Alternative unit of measure

Suppose I have a base unit KG for a material and alternative unit of measure Lit for this material and we have maintained a relation for that.

Now suppose this material is coming from 2 vendor but due to some quality problem the material is coming from venor A and Vendor B are not same and the relation of KG and Litter may differ for 2 vendor.

Now when I am making GR against this 2 vendor the quatity may differ due to the relation differ.

How can I handle the inventory against the AUM for this material?