Tabs within tabs

Hello!

I'm looking for the simplest way to build a "tabs within tabs" slide like the one attached. In the past, we have done this with variables controlling visited states (each layer had its own set of sub-tab buttons). This works fine, but involves a lot of triggers and potentially unique variables in a file. We can keep doing that, but I'd like to crowdsource and see if anyone is doing this in a more elegant way. 

I started experimenting with keeping sub-tab buttons on one layer and using the built-in states, but those states are working as described :) which probably means it isn't ideal for us. When someone clicks 1-A, 1-B, and 1-C, then clicks tab 2, then clicks back to tab 1, we'd like all three of the sub-tabs to be in their visited state and the content they see be the content from tab 1. (Let me know if I've mangled that explanation.)

https://360.articulate.com/review/content/8ee124b5-8611-4746-b3d2-e3e7de2201dd/review

Thank you so much!