How do I seperate two sets of triplets?

Hi,
Sometimes two sets of triplets somehow become connected, so I cann’t change one of them as I wish. In this case, I want to delete the second one but either I delete both of them or I delete the notes I select, and then the notes after this triplet get changed into triplets.

afbeelding

This is because it’s actually one triplet of crotchets/quarter notes, spanning the barline (Dorico can do that). Either choose eighths first, then enter 3:2, or explicitly tell Dorico to create a eighths triplet by entering 3:2e into the tuplet popover.