Conversation Suggestions - avoid suggesting things said

I’m digging in to Eric Eve’s Conversation Package and came across something I need to solve.

Is there some simple way of checking whether a thing has already been talked about? What I’m doing is basically that in the “response for N when asked about X” the character (N) mentions something else (Y) and so I add that as a suggestion to ask more about (“add Y to the ask-suggestions of N”). But if the player has already talked to N about Y I’d rather not suggest it. So I’m looking for something like

response for Bill when asked about the journey:
    say "Well, we just took the carpet for a spin. ";
    [if the carpet has not been mentioned] add the carpet to the ask-suggestions of Bill.

Is there some way of doing that “if the carpet has not been mentioned” clause?

I haven’t used the whole package, but when I was working with Conversation Responses, I did have to add this:

A thing can be discussed.

…and then at the appropriate place in conversation code:

now the noun [or the second noun] is discussed.

I usually would hold off on making something discussed until an NPC actually says something substantial about it.

To enable multiple conversations, I’d set everything not discussed at the beginning of a scene. But if you need finer detail, you might have to use a many-to-many relation:

Discussion relates various things to various people. The verb to be discussed with implies the discussion relation.