Two named people on railcard must travel together.
If this is a correct rendering of the condition, it would suggest that the conditions haven't been adequately thought through.
The economic point of selling tickets is to raise income to set against costs. Discounts are offered to generate income, e.g. by attracting customers (and their money) who wouldn't otherwise avail themselves of the services offered.
In the case of a Family & Friends railcard, I can see the argument for saying that discounted tickets bought for an adult and a child shouldn't be valid for travel by the adult alone (e.g. where the child is not well on the day) as then the adult would be travelling for 86% of the price of undiscounted travel for a single adult without the railways gaining anything from having given the discount.
But ... if I buy two adult tickets with a "Two Together" discount, I pay 132% of the cost of travel by a single adult alone. If on the day of travel, the second adult is not well and I travel alone
with both tickets why should that not be permitted: I am paying a premium for my solo journey.
Similarly with East Coast's small group offer (where the conditions are decidedly unclear as to whether the 25% discount is for buying three or more tickets or is for travel by three or more persons together). If buying advance tickets with that offer for 3 people, who knows whether one of them will be ill (or have ill children) in several weeks time. The three tickets cost 225% of a single adult ticket, so if only one or two members of the group can travel on the day they are paying a premium: what's the problem with that so long as they present all three tickets?
So for Two Together, or the small group offer, I think that the conditions should make it clear that the discount is for buying the multiple tickets and that, if one or more of the group cannot travel on the day, the rest of the group are entitled to travel using the discounted tickets so long as they have
all of the tickets with them and present all of them for clipping.