Hi Anna, thanks for joining the forum.
Since I’m not sure I understand what your asking, please let me know if this answer helps.
KCSB uses Spinitron’s automatic music recognition feature. If your future playlist has the right start date/time and duration then Spinitron will automatically use it to log recognized songs. There’s nothing else you need to set to make this happen. It’s Spinitron’s normal behavior.
But it doesn’t “just insert timestamps”. It inserts whole spins, each with timestamp, artist, title, release, label, cover art etc. Spinitron isn’t able to match a recognition against the spins already in existing playlists, estimate degrees of correspondence, choose the best match and update its timestamp.
When Spinitron has a new recognition, it finds an existing playlist (or creates one if needed) and inserts the recognized song into that playlist ignoring any spins already in the playlist.