Separating/Joining tuplets into smaller/larger groups

Basically exactly what the subject line asks. I've been wondering if there's a way to have a tuplet of a given duration (in my case, 16th note sextuplets in 4/4), and to separate it into 2 smaller groups of tuplets (in my case, 2 groups of 16th note triplets). I ask because I had a problem halving the duration of a run of 16th note sextuplets, and I didn't want to rewrite out the whole run, and an easy fix for the problem would be to regroup the tuplets. I've attached an annotated score with an example of what I am currently able to do, and what I wish to be able to do. If there's already a way to do this, fantastic! Ignore my suggestion, and please tell me how to do it. But if there isn't, then consider my suggestion please.