Hi Kristin,
I just replied to an email with a similar question. Let me copy and paste my reply to see if it helps.
Like I mentioned in my reply earlier, there are two types of iPart factory. One is called regular and the other one is custom. Regular iPart means all definitions are clearly articulated on the iPart table. You can only alter the table content or the factory in order to change the member. The member is like a readonly component. It cannot be changed by itself. The so-called “proxy path” applies to this kind of iPart. For example, in your project Library setting, you have “iPart Factory – 2000” and “_iPart Factory – 2000” respectively. The former stores the iPart factory files. The latter stores the regular iPart member files. If you don’t have this proxy path (‘_’), the default location to store the member files is under the factory file name folder. For example, you have a regular iPart factory called “XYZ.ipt”, the default, non-proxy path for its members would be \XYZ\.
For custom iPart factory, which is what you have right now, there is no need to define proxy path. It is because custom iPart members are just like derive parts with a link to the factory part. As long as the factory part can be found within the project, the custom iPart member file can be stored anywhere within the project. This is because the custom iPart members tend to be project or assembly specific. Custom iPart members, unlike regular iPart members, more than likely can be used by the particular assembly.
Please let me know if you have additional questions.
Many thanks!
Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer