Support for, One line with Multiple Solenoid Support

I think Rachio can be a great if we have One water line with multiple solenoid support.(more zones)
I have 16 ch one but so far got 6 channels active with 4 on one tap and other 2 on back of the house tap.
Considering weather changes, I need to modify my zones and add few more but since paving is done I cannot dig and put new pipes.
But there is a way to do this.
If I can add a few solenoid to existing line then trigger them as different zones it will save me digging up the whole garden.
I can easily connect solenoid 24v ac wires but cannot connect plumbing to existing taps due to pavers.
I can easily cut and add solenoids in the garden beds.
Ideas is create 2 zone to 4 zones. Keep one line as a master it add 3 more zones to that line.
Hope I am clear on this scenario.
Since I have 2 taps, I may need 2 Masters. But if I have to add one each solenoid for 4 lines I may need 4 masters.
Hardware wise, I think Rachio can do this but need to change the App.

@siri, thanks for sharing your ideas. They sound very interesting. If I’m understanding correctly, you’d like to have sub-zones within a current zone. i.e. Zone 2 becomes Zone 2a, 2b, 2c, etc?

Pending how many additional zones you need to add, the Doubler might be workaround for you that currently exists. I don’t know if we have any users with a Doubler installed, but we’d love to test one with you if you think this would help you.

Tks for the info and it looks interesting… Any Rachio user here use this product?