I would like to understand the difference between in the discussion and at the discussion. Could you help please based on my own sentences?
In the discussion the participants considered the issues related to competitiveness and socio-economic divisions in the European Union.
and
The participants at the discussion considered the issues related to competitiveness and socio-economic divisions in the European Union.
If I want to mention that someone participated in the discussion, should I use a phrase X in (or at) the discussion (only a phrase, not a whole sentence).