To set the scene I work for a medium size company which has 20 different offices/branches across the south east which I have nothing to do with.
In my branch we have 3 different teams, plus a management team. Each staff member is based in their own team and has responsibilities for that setting but it wouldn't be unreasonable for them to have to cover in any of the other 2 teams for example due to being short staffed or to cover lunches etc. So 95% of the 40 hour week we are in our own teams.
Team 1 has 6 staff members, Team 2 has 4 staff members and Team 3 has 4 staff members adding management there are 17 members of staf of in total.
We all socialise together every couple of months BUT..
Is it unreasonable for 6 staff members from different teams (a mix of all 4 teams) to meet for a meal on a non work day?