I have a video clip that 3d camera tracker cant track unless I split it into segments i.e. dupe and trim then the 3d camera can solve each section.
I can then create nulls and pickwhip objects to the nulls using the toComp expression all is great until I get to the end of the first section of video and the new camera takes over is there a way to link the nulls from the first tracker to the second without supper fiddly trying to align the nulls on the first and second parts of the video.
If I get you right, you want to have all tracked keyframes on one null object. If yes, maybe try selecting tracked keyframes from the second null, copy them to the clipboard and then paste them on the timeline of the first null at the end of the last keyframe. You should get one null layer with all tracked keyframes on it.