Hopefully this is a step in the right direction…
I just added some more stuff on the end, making use of the joiner regex component.
It currently leaves gaps, which means that a new “grouping” always starts on the same line as other new groupings. This is just the way the method I used ends up doing it. That may be what you are after. If you want it “squashed up” so the blank cells disappear, I’ll have to think about that. There are forum posts on the subject, such as this one, but I haven’t thought this through any further to say if there are alternative approaches:
And now I must dash! 
GroupBy-alternative with regex join component 2.knwf (221.9 KB)