How is the return defined? Does it have to be the reverse of the outward journey?
That is the standard definition of a Return, yes, and the way you need to use it.
As you rightly state, this is simply a gesture of goodwill, they weren't required to issue it. You can travel on your own, you don't need to take 'the family'.....Put ity down to marketing, if you like.
Give it to someone as a gift if you don't feel you want to use it - earn brownie points.