Manual Track is Removed When Importing Another Footage?

Hi,

I have 2D tracking in Cinema4D using Manual Track.
When I import slightly different footage, the manual track is deleted.

Is there a way to keep the manual track after importing another footage?

Illustration background is I have given change 520-820 (300 frames) to track. Now it was changed to 500-350 (350 frames).
I was expecting to use my previous manual tracks since both frame range have more or less the same visual detail.

P.S. By manual track, I meant their initial position (so I don’t have to recrete them again) rather their whole track data.

Regards,
Ben