I just change the program to run in triplet mode {Notation>options>Triplet resolution} when I want he triplets, and turn it back to 16th when I have finished. The print out is crappy, but the notes are evenly spaced, so they sound OK. If the printed output is important, just pick a swing style for printing and back to the original style for playing.

There is a way to change individual notes to / from triplets, but I always found more cumbersome


BIAB for Windows Version 2019 (643)
Windows 10 (1909)