About four years ago I booked the whole family of 5 of us to the West Coast in F, using 2 different 241 vouchers and one straight miles ticket. Now both of the 241's were in my name as the sole Amex cardholder in the house. So this was an A+B and a C+D (where the holder of the voucher was A) and then E on its own.

This was booked by phone and I was advised that provided that A was on the flights then C+D could travel on A's other 241.