@stefanod sure please find this repo for form examples: https://github.com/RasaHQ/rasa-2.x-form-examples (in 2.x) try experiment with this? thou personally I have not started exploring rasa much as my bot is in production, and I am working on 2.8.1 only. I hope this will help you. Hope this will solve your issue?
Further, there is much change in forms, but yes ref the Rasa 3.x Documentation and try implement your use case.