well, it seems that the Normans entered Italy as mercenaries, in Lombard service, sometime between 999-1017. though it was not until 1020-1030 that Ranulf Drengot was granted
Aversa as the first Norman fief in Italy. while in the 1040`s William de Hautewille was given
Melfi.
this mod ends in 1071, at which time the Normans still were not much more than a mercenary army based at a few holdings in southern Italy.
i do believe it is still to early to recruit Normans outside Italy, and no reason why there would be a connection to Serbia or any other single nation in particular.