Part connector nodes not showing through nested families when loaded into a project with Revit MEP.
This is a current limitation in Revit… There are a number of workarounds, one being placing the connector parts in the host family and setting up the system types there. However this can cause problems and limitations elsewhere, so at the moment the best working solution is NOT TO DO IT! Instead place your connectors onto the relevant parts, load into your project as normal and then use the grouping option to get the elements move as one. Although this will increase the project size slightly, compared to the first suggested option, the actual number of grouped elements needed will be quite small. Therefore, the file size increase should also be minimal.