My angel fish are being VERY agressive.?

We recently bought a 70 litre tank, and had two angel fish, 7 neon tetra and a litttle red tail shark, it was calm and normal in the tank, all fish settled in well. We left them for a couple of days and today we added two smaller little angel fish, and some danios. One of the big angel fish is being VERY agressive towards the two smaller ones, chasing them and ramming and swimming into them very fast, acting very territorial and angry, help! what do we do, we just want a happy chill, and freidly community within the tank, and the big fish are being bullies! we have already tried taking the big bully angel fish out into a seperate tank and then moving around the plants and pebbles ect and releasing the angel fish back in but, it did not help...PLEASE HELP!