Whilst it's possible to use the grips to edit a path of a vehicle, there's no option to add extra grip points. Nor can you continue tracking from an existing path (either by creating a new path from the end of an existing path or extending an existing path).
Whilst Drive may not be a significant part of your software suite, if Drive could have more functionality it would mean that users of LiveDesign would have one less reason to use other design software (for example AutoTrack or AutoTURN)