! I'm so sorry you lost your bird to a hawk 
But I totally agree with what others are saying - it would be best to let them get used to each other through a fence first for awhile, at least until they're older. Sometimes they're able to sort out the pecking order with posturing and never really go at each other when you put them together! When I first got my polish hens I left them in a pen on their own where they could see my other girls for a month before introducing them, even though they were grown. When I let them out, the birds only scuffled a little and all was well 
They had managed to start sorting the new pecking order out right through the fence without any fighting.
