I have created a new Product Type and added two new fields named "Weight (gram)" and "Weight (pound)". I would expect the store owner to provide data to at least one of these fields and I want to calculate and enter the missing part of the pair on the fly.

I thought I could use rules to achieve what Im looking for but Im having problems to select those new product fields on the rules list to be able to set some actions. My new fields are not visible under Commerce Product section, nor under Data Compression. I can only reach those fields through Entity by Property section but then I again can not see those field when Im trying to set an action.

Am I missing a setting or a module to be able to fully use Rules with my new.custom fields on the Products?

Do you think I am on the right track? Is there any other way (or rather say a better way) to achieve my main goal?

Thanks...