Hi Lesley,
I have heard that most of the adoption rates are based on full fare (not economy), so even with the discount the tickets are usually more money than you could get if you bought a restricted ticket. But, if you need to change the flights around, the full ticket with the adoption rate may come out to be cheaper (but probably not by too much). I am just relating what I have heard; I am not a travel agent or anything.
HTH.
Have a wonderful trip!!