Dataprep should make up it’s mind if it wants to be Blueprints or the old particle system stacks.
Right now, it’s a Frankenstein in-between thing, with literally zero hints of stacking (unless you happen to mouse over in the right place).
I had to look in the documentation to find out about the stacking.
Why not make all Dataprep nodes to be regular blueprint nodes instead, and enable loops, if-then, custom string matching and all of that other good Blueprint stuff that you can’t possibly take into account using the limited rules of the stacks?
If Dataprep is going to stick to it’s stacking in the future, then I suggest removing the Blueprint connection lines alltogether, because they suggest something that it’s currently not.