Keeping track of original commercial part after modification

Hi all,

In the various projects I am involved, there are some commercial parts (valves, bearings, etc) available for our machines which I incorporate into SW assemblies. However, some of the more generic ones must be modified in some way to fit the machine (such as drilling a hole or cutting off excess material). Most suppliers give us their parts in 3D, which I then modify in Solidworks. However, I would like to keep a copy of the original and and somehow have the modified version linked to it so as to facilitate the creation of the list of materials to order. So far, the best solution I have come up with is importing the commercial part as a solid body into another part document and make all necessary modifications there.

How do you keep track of the commercial parts and especially any modified commercial parts in an orderdly fashion?

Kind regards.

SolidworksParts And Features