How does one, within an 8th note triplet, enter a 16th note triplet to fill the first tripleted eighth note, like this:
444 5 5 where the whole series is a triplet spread over one beat (5s being eight notes and the three 4s comprising a 16th note triplet spread over 1/3 of the original one beat)?
Start with the outer Triplet and work inward.
Enable Input mode <Shift>N
Enable triplet mode ;
Type 3:2e into popover
Select first 8th note in resulting triplet
Enable triplet mode ;
Type 3:2x into popover