One of my friends has recently brought a Z fare and has now decided she'd like to join us on our flight - can she do this on this ticket? if so, are there any penalties?
Well, they can certainly joing you on your flight, providing they're on the same flight as you already
Otherwise, it'll be a call to Virgin - but to prepare you for the likely outcome, UK & US based Z fares are officially non-refundable and non-changeable.
The only way to "convert" it into a changeable fare will be to upgrade it to a FULL J fare. That'll be in the order of 2-4x the cost of the original Z [:0]
Also, it this fare was booked through a travel agent, it may not be changable at all. Call premier and ask, and be prepared for your friends to go back to their travel agent to see what they can do.
I thought this was the case but she was determined she'd only have to pay a small penalty to upgrade it, I'll ask her to call the premier team as she never believes a word I say.
Your friend COULD be right, with regards to changes, as some travel agents have a great agreement, but MOST Z fares cannot be changed, or need to be upgraded to the J Fare.