Your comments

Model driven app already currently supports this..  you can see from this example

Now this is in the gallery, can we change the status to completed Guido?

Only challenge I can see around this is, that stages also must take into account mandatory requirements also before they're allowed to progress.  But I like the concept.

Better off binding it to an entity TBH, that way the control isn't context aware.

I had a similar request, but with charts instead of subgrids.  Currently it's not straight forward to inject fetchxml into a model driven chart, and the client doesn't want to fork out for PowerBI (for 5000 users).