You can flatten a multipart path down to its constituent parts making them individually available for editing. If the path is made to be choppable, I believe that some parts could be choppable whilst others are not, so you might be able to Chop parts of the path without needing to flatten the MPP. For a bus, if you wanted different lengths, say at the end of the path after drawing or stretching the path, the offset subpaths could each have different begin/end offsets and even different widths - the sub-parts of a Multi-Part Path can have different attributes, they do not all have to be uniform at all.
Here is the link to Solution 11252132
I hope that this helps,