If you check "Allow several bill of materials per products using properties" in the manufacturing settings, you will be able to specify several bill of materials to a single product and specify properties on them.
In Manufacturing => Configuration => Properties, there is a "Properties composition" field that can take several values: min/max/plus.
Does anyone know what those values represent, functionally?
For the life of me I can't find any code that operates on the values in that field. In 7.0 the help text even states that the value is NOT used for computation. In a broader sense, the mrp.property object seems to be an incomplete framework that requires python code to expand on it in some way to make it useful.