Grave Robber uses mix of API and user interface control.
Selected sequences will be opened one by one, clips inside copied to clipboard and after pasted to the main sequence.
Grave Robber will respect in/out point of nests, so no extra media will appear in the main sequence.
Grave Robber accounts for clip conflict, if there is an obstructing clip above a nest in the main sequence, new tracks will be added for un-nested clips.
One can make a rough selection that will contain not just nests, but other clips as well (video, audio, essential graphics). Grave Robber will filter out non-nest clips and continue to un-nesting the rest.