How to increment all time offsets by same amount?

If you increase the length of a keyframe near the start of a project then all the keyframes to the right of it get ‘bumped up’ by the change in length. But if the future keyframes have waypoints that set a time offset that time offset is not ‘bumped up’ too. Is there a quick/consistent way to bump these all up?

For some background: I have a few videos imported as .lsts which are all intertwined (next to each other and overlapping) and there are precise adjustments to their offsets to keep them in sync using waypoints with constant or linear interpolation. I want to insert some time and have all the .lsts move forward by that time.