Maybe I am misunderstanding but wouldn’t you want the markers to remain glued together, as separating the markers would make for gaps between the tracks in certain situations?
You can click on a marker in the markers tab to change a splice marker into another type of marker, but you’d have to add the “other” marker manually. For example, if you make a splice marker into a track start marker, you’d have to manually create the track end marker for the previous track. I don’t know of a way to automatically split a splice marker into and end/start marker combo.
If you want to make a montage with negative time between tracks then you wouldn’t want to use splice markers.
Not using splice markers can cause issues though. If you make a DDP or CD-R, everything should be fine. If you need to render WAV or mp3 files of just each track, then the pause between end and start markers will not be included and will alter the space between songs when you load the files into other playback software.
Personally, I only use the splice markers and arrange them so any pause is part of the previous track, leaving around 200 too 300ms of “air” before the first audible sound of the following track.
The way that iTunes and other playback/streaming apps handle negative time/space between end and start markers has caused many mastering engineers to just use the splice markers and keep most of the pause between songs as part of the previous track.
Negative time was fun when CDs were the main format, you could put noises or fun things between songs but not officially be part of any track.