Nous avons commencé à discuter

Bonjour Ian,

Your suggestions are great options and would absolutely work in this context - although "causer" is rather familiar. In this particular case, being a writing exercise, it can be tricky at times to add all the possible options. That's why "bavarder" and "causer" haven't been added to the answers there.

I hope this is helpful.

Bonne journée !