fighting

Hello all!. New member question: I have two kids- Woody (male) born 10-22-11 and Stella (female) born 07-05-16. Up until about one week ago, they have been best friends. Out of the blue, now they are not getting along at all and fighting- not wrestling like they used to do all the time, but sure...

We recently adopted another male Bulley from the same litter. They are both 2 now and one (our original) is being quite aggressive to our newest family member. He is usually very sweet and we are concerned and hoping for some advice as how to handle these two brothers. Any advice will be greatly...