Hi JipHollanders
My name is Daniel. I will be more than happy to assist you.
Do you still remember the keyword or topics you discussed in that group chat, if yes try to enter it in the search bar. Select Message tab > select chat (see screenshot)
Disclaimer:
This is a peer-to-peer support forum. I'm Non-Microsoft Staff, I don't work for Microsoft. Mostly everyone here are users, helping other users.
Kind Regards