Fill a slot with message regardless of the intent detected

Hello. I am trying to achieve a goal that I thought should have been very easy, and instead I am not finding a solution anywhere.

I have a non-required from_text slot called “notes”. When a form ends, I’ll ask if the user wants to add notes. If they say yes, they are asked to type whatever they want, and I want to save this in to the “notes” slots.

Given the huge variability of the text that can be sent, I think it does not make sense to train an intent model for that. I would instead force slot filling at the specific moment in the conversation. Since I ask explicitly if they want to add notes, I know exactly when such moments happen in the conversation.

However, I do not know how to tell Rasa “After you ask the user to type their notes, take all that text and fill the slot, regardless of the intent you guess from the message it self”. Is there a way to do so?