Hello Ian,
I am not a navy man, the group I referred to belongs to a friend and is not mine, I agree with you, the condition of the QSA should tell you in what order these were worn, much like a Egypt pair, at is the bronze star that does the damage, a close look at the recipients Seamans Statement of Service or HMS Terrible's Ships Description Book may well prove worth while here.
But either way I would not worry about it, still a good group, medals to members of Terrible's crew who served ashore in Natal are worth having whatever their condition, the third China War medal is a bonus in my opinion!
A very good honest group and well worth having, I should be very pleased with it if I were you, the QSA its self is nice but you have all the other medals too!
Regards Frank