I agree with the Members here who advised you to keep them seperate for a while so they can get used to eachother, U2s have lots of dust and is very bad for Macaws, so you may want to invest in an air filter and keep it next to your U2s cage so this will keep the dust down.
Your B&G is going through lots of changes right now,so slow down his world, spend lots of one on one time with him, give him the chance to bond with you and your Family first, then see how your U2 and B&G interact with eachother.
As far as his diet, Some B&G are smaller then others, Have a Vet take a look at him to see his bone structure and what weight is good for him.
Fresh fruit, fresh Veg are very important here, a good brand of Pellets like Zupreme or Roudy Bush. Seeds and Nuts should only be given as treats a few times per week, not everyday.
You can give them Almonds when training him, the fastest way to a Macaws heart is through their crop. Best of luck and keep us posted on his progress. Joe