And, as I discovered recently, a Senator (me) can have the joys of being forced to sit at the opposite end of the economy cabin from their partner (BD gold) who was on the same PNR (a M&M award booking).

Apparently benefits of preferred seating (emergency exit and front rows of economy) extend only to the Senator member, not those travelling with them on the same booking.

No problem, I thought: I'll move myself back to sit with my partner. Wrong. The LH online check-in system had other ideas and refused to let me pick anything other than the seat it had allocated me, crashed, and then decided check-in was complete and we were stuck with the seats auto-assigned to us.

Never have I come across such a useless implementation of a check-in system.

A further "quirk" is that if you have made an award booking and used your frequent flyer card as the id, then you can't even check in together. You have to check in each passenger on the PNR separately.