Thank you!
The first thing to realise is that a lot of Transform’s power rests on its ability to select which particular messages a given Transform will deal with
Midihub’s different ranges are contrasted here but this is the crucial image:
(anything outside the range(/channel) of a given Transform will simply continue, perhaps to be used by a subsequent one)
maybe this analogy will help:
Think of a pipeline as a conveyor belt carrying messages down it, with Transform workers stationed along it.
Let’s take Scenario A
Each worker deals with only one PC
(they are thus nicknamed Workers “1”, “2”… “6”, “11”,“12”, & “17”)So PC#1 arrives and Worker “1” picks it off the conveyor and replaces it with one of his collection of CC#115’s (they are all set to value = 5)
but when a PC#6 comes down the line, all of Workers “1” thro to “5” just think “not mine”, ignore it, and watch it go by…
…leaving it for Worker “6” to remove it and replace it with one of her CC#115’s which are all set to value = 9
and so on
note that all those other PCs (eg. 8, 31, 99) will just travel on past all the transform workers and need to be dealt with later…
Hopefully, this analogy works for you.
If you come up with one that works better, please share! 
PS. For completeness, I should add that there’s a scenario C where we don’t need the PC → CC → PC trick but use Drop Transform(s) instead. I may add this when you’ve solved your set-up