Dual Unit of Measure

We are currently on 8.12 app and 8.98.4 for tools and have a regional instance architecture. NA (U.S., Canada & Puerto Rico), EMEA (Many Countries), Latam (Brazil) and APAC (China & Vietnam). We are now deploying in LATAM to the southern cone (Argentina, Chile, Paraguay and Uraguay). Executive mgt wants to not increase the number of E1 instances and wants to have 1 Americas Instance.

My question is, our NA markets use Imperial unit of measure whereby everywhere else in the world it's metric. This is primarily for raw ingredients and raw materials. Finished good use Each (EA) everywhere so that's not an issue. If we combine a Imperial UOM market with a Metric that would cause a collission at the Item Master level. I tried to test Dual Unit of Measure functionality but all inventory related transactions used the primary UOM which I had set as KG and set the secondary UOM at Lb's. But all inventory transactions I tested used the primary.