Function calling use case

I have a use case, where the model has to output two types of responses

  1. {type:“string”,content:“string”}
  2. {type:“audio_based”, content:“string”, follow_up_questions:“array”}
    So the model has to sometimes give a JSON output with the 1st schema, while sometimes the second schema.
    Now how do I do this? using function calling?
    if at all I do it, how do I pass it back to the model again via api? I mean I am not actually calling any function right, I just need the data in that format.
    What approach do you guys suggest.