Awww, jealously already? It's just gonna take time and patience. I have 5, and they just have to adjust to a new baby being around. Maybe try to keep them seperated when you're not with them; and always show Buddy attention first, first treat, first toy, etc. Before you now it, they'll be best buds.
Btw, have they both been neutered? If not, based on experience, that will work wonders. Good luck!
