Controlled generation

Hi!
Thanks for the amazing job!

Have a couple of quick questions. I'm trying to use mT0-xxl-mt for QA. When I provide the context and ask a question, subject of which is not presented in the context, the model anyway provide something from the context even if it's totally wrong. Ideal scenario in this case - is if the model could output like 'I cannot answer this question with this context" or something like that.
1) It that possible without hard training on additional data?
2) Bias matter question. If I train the model on additional data, would the model still provide "good" answers when the subject of question is in the context?