Jean: La semaine dernière, Louis et moi, nous SOMMES ALLÉS_au restaurant avec les cousines de Claire.
Once there are 2 subjects (Louis and I) the past participle is PLURAL We don’t know who is. MOI but it doesn’t matter because Louis is a boy and when it’s plural and at least one is masculine, the past participle will be masculine plural
Only when all the subjects are girls the past participle is feminine plural
