[Well. This is interesting, and yet....Still, there's a contradiction there. One, perhaps, Yukio himself does not want to face.]

Yet, you still want to bring him back to life....ah, well.

[For now, he lets it go, bringing his attention back to the question before sighing.]

A man named Marisbury Animusphere summoned Solomon as his servant for the war - and, at the end, refused to use the Third Magic the Grail is meant for, allowing himself and his Servant a wish. The Servant wished to be human - and so he was, but not as himself. He became a new man who knew of his past self, but looked very different and did not consider himself as 'Solomon.'

I cannot speak as to if it would be the same for all Servants. But....are you willing to have your brother be 'reborn' into a new life? And, not only that....but for your wish, you would have to kill him yet again.