Saving utterances in bot Universal bot

Hi,
I have 3 bots (IT, HR, Fallback) which is linked to universal bot. When operating through the universal bot and any related utterances triggered for IT or HR bot provides me the responses but if any unrelated utterances take me to the fallback bot. What I require is, the unrelated utterances when triggered through the universal bot should be saved in the Fallback bot.

How can I achieve this?

Thank you.