You need to install FoV first, then the DKS conversion patch. With FoV you will be able to continue with an existing D2:ED save, but there were too many changes in DKS to maintain saved game compatibility. After installing the conversion patch you would need to start a new character, either at the beginning of the D2:ED section, or a new level 35 character at the beginning of FoV.
D2:ED + FoV vs DKS?
