I don't "see" the problem ...
You can buy the full Dragon Knight Saga (Ego Draconis + Flames of Vengeance) at a cost of 40 €.
Only the add-on, FoV give you around 30 hours extra gameplay ! It's a "game" on his own
.
Plus :
you can choose to play first Ego Draconis (remastered!)
or
you can immediately start from the beginning of Flames of Vengeance with a Level 35 hero
So NO saves from Ego Draconis needed to begin playing Flames of Vengeance on your Xbox360 !
Naturally you can play Ego Draconis over again and play further on, seemless (!) in Flames of Vengeance, taking weapons, gear etc from Ego Draconis with you ... .