In the Export vGPS options please add a new option "Copy to vGPS" This would open a select box titled "Add to vGPS", listing all the vGPS (excluding the current one). Include a warning about maximum vGPS size. Perhaps add an option at the top of the list for "New vGPS" for convenience, however we can pre-make the new ones if needed. Selecting the vGPS would merge the current vGPS with the selected vGPS.
This would allow us to merge vGPS files, or spit a vGPS file (by copying it to an empty vGPS and then removing the unwanted portions from each)
Currently this can be done through bookmark lists, but is a more difficult and considerably less intuative process.