Give the option to change or keep the unit of measurement on an item thats being replaced with something using a different unit of measurement

This one came from an example where I only had one rate build up for an item but it was in a different quantity, for example a partition that was measured in lm and height categories as opposed to m2. When I changed the build up to the opposite it would change the UOM which was obviously no good, so my thinking was when you do click on something of another type of measurement instead of automatically changing it, you have the choice to stick with one or the other, from then it might be advantageous to have the conversion scale set.