Here is a short video of both sequencers running..

The first sequencer does a sequence I continually modify while It is running BUT I keep the first stage active while I add or remove others.
The first stage output is routed to the second sequencer's SHIFT input Thus advancing it every time the first seq goes to its first stage.
Doing so I hear a varying melody (seq#1) accompanied with A running bass note (seq#2 ) once every start of melody.
Both melody and bass line are generated using different VCO's and filter settings.
The seq#1 melody's number of active stages is varied along its playing.

https://youtu.be/JNH-ZRiqYIw