Since you're already using VCV, why not get an Expert Sleepers ES9 so you can compliment the growing rack with whatever you need - I still rely on VCV for the end mixer and a lot of end of chain effects, not to mention modulation CV sources from VCV back into my physical rack. I also use VCV scopes for visualizing modulation - somethimes with a bank of 8 or more on bigger generative patches, endlessly fascinating... I'm not interested in performance so incorporating VCV with my desk-bound system is a no-brainer for me.
Other thing to consider - are you planning on taking your kids on the modular journey? If so maybe some bigger modules is a good idea, for ergonomics and clear workflow etc (I guess I'm referring to the drum modules, the other modules look great for learning)
Finally, consider a Noise Reap for your second VCO. You get two oscillators and normalized freq control between them. It's analog and can get really dirty so could compliment the digital Plaits.