Tool box customisation and properties

I have the material in the tool box part.

I have put in the Property Mass and “SW-Mass” in the property the parts generated by tool box are sperate parts not configurations the issue I have is the “SW-mass” does not automaticaly update the the mass of the part unless I turn read and open and save the part.

so I end up with

yet the part is evaluating to

image

the other issues is the mass is set in g in the standard tool box parts i need it in KG this means I have to open the default parts in read write change the units save them and set then back to read only.

Is there a faster way to change the properties through a Macro?