I guess all of this transition have to start from the time you are pregnant.
Although I try not to hold my son when I was pregnant with my daughter, but
I always play with him, red books and hold his hand. Tell him mommy can't
hold him but I can hold your hand and walk with him. And then after I gave
birth, still try to play with him as much as possible and if possible get
him involve with taking care of the second baby, although it might be hard
but try to have them do something while you take care of the second hand in
that way he feel you are still paying attention on him ... will hurt less.
But totally agree that their personality change more or less after the
second one come out =P