My idea is to create a new FormAction just for these child-slots and train rasa just to ask for these when the parent-slots are filled. But then there is no 100% certainty that this will work.
okay in case anybody is curious, I think what I searched for is Custom Slot Types. I think I get the example in the documentation but do I also have to do it with boolean typed slots?
Then it would be something like [0,0],[1,0] and [0,1] for unset, true and false - right?
I think two different questions here
a. If you need a field required based on another field , then the out of box FormAction doesnt do that. However you can extend it (or write your own to do that)
b. For boolean type slots unset as false are treated the same and true is different so if thats also you want to base the next action on then you dont need a custom slot.