Looking for some general information on Delta's reward booking stopover and layover rules.

There are four cities:
A - origin
B - random city that is a connection on a published fare between A and D
C - random city that is not a connection on a published fare between A and D. However it is a connection on a published fare between B and D.
D - destination

Let's pretend for a minute that layovers are not allowed. In this case, I understand the stopover rule to be: You can stop over at a city that is part of a published route between your origin and your destination. So you can do A-B-D here but not A-C-D, at least that is my understanding.

Now let's add layovers into the mix. Am I allowed to fly from A-B, layover in B, and then go B-C-D with a stopover in C? In other words, does the layover "reset" the origin city and allow me to access other stopover cities?

Thanks.