Make testing the focus
For a given feature that you are discussing, as a group, go through what you plan for unit tests, integration tests and end-to-end tests. Talk about how you will do performance, security and usability testing for the feature.
Discuss what makes sense to test manually and what makes sense to automate
Discuss which tests you should ...
This is an example of building a software system for the marketplace. In this case, you have many customers or users, each of which has its expectations for the system. However, someone must have identified that there is a need for the product in the marketplace. If someone did not justify the possible need or desire for the product, how did anyone fund the ...
One of the ways is Example Mapping.
All you need is a pack of coloured cards and pens and preferably a table.
Write the story on a yellow card and place it at the top of the table
Write the acceptance criteria and the already known rules on a blue card beneath the yellow card
Under each rule/AC add green cards with an example that illustrates it
I'd also add that seeing the story beforehand is a good way of making the Three Amigos session more likely to provide benefit.
Thinking up questions and issues on the spot when you've only just seen the story is a lot harder versus having a day or so (or even an hour or so to be honest).