FYI, when some Companies' pay for employees' to travel FOR THEIR WORK, Business Class is what is booked. Maybe the spouse can travel same class, maybe not. But any kids' are paid for in Economy. They are deemed 'Unaccompanied Minors', by the Airline, as no responsible adult is travelling with them in Economy. UM 'paperwork' is filled out by airline booking clerk in computer, at the same time as plane seats booked.
This is NORMAL Airline booking procedure. Happens constantly, as Companies' want employee to 'work' on flight, or arrive at destination, 'refreshed', without having to have looked after kids' in flight.
Again, this is 'normal' procedure IF Companies' are PAYING for employee to travel for their work. THEY stipulate who flies in what class. It's not up to their employee to choose the air travel seating arrangements, as the employee is NOT paying the airfare.
And before you go all 'indignacious' out there in 'comment land', be mindful that an employee usually can't have 'a say' in way of travel, & neither can his/her spouse, in these circumstances. If spouse starts any ruckus at all, the job of partner could be in jeopardy.
The base line here is, whoever pays for seat/s, 'calls the shots'.
As to question 'who looks after the kids', the Airline Cabin Crew do. Hundreds' of UM's travel everyday, Domestically & Internationally, & are very well looked after. Airlines take this responsibility EXTREMELY seriously, as they should.
A parent in Business Class CAN go back to see child in Economy, but the reverse is not permitted. Airline Policy, so please don't try & 'argue' the point. It's been like that ever since, & won't be changed.
Oh, BTW, same situation applies with persons' travelling on holidays'. If they can't, or don't want to pay for kids' in Business Class, same UM procedure applies. Yes, again, it's 'normal' in air travel world.
And to those who think 'who would do that?', I can assure you it happens constantly. How the 'other half' fly, eh?