Aggression... I brought it on myself!!!

Like the title says totally my fault, but im not sure what to do now... Got a IT last week around 3 inches long and i liked it so much i wanted to get more... I knew 2 wasnt a good number and a lot of what i have read says 3 or more, so i ordered another 2. They arrived today and boy is the original one not happy!!! The 2 new ones are a bit smaller than the old one, about 2 inches and 1 3/4 inches. They are being chased mercilessly by the original. I figured on a bit of chasing, to see who was boss, but never expected it to be constant. Admittedly its only been 8 hours, so Im wondering if it will settle down any? Would getting a 4th really make that much of a difference if the original is such an ass? Im going to re-organise the decor and see if that helps, but any suggestions? Am i best off cutting my losses and rehoming the 2 new ones? Or like i said would a 4th help? They are in a 4 foot tank at the mo, to be upgraded to 6 foot beginning of next year.

I redecorated last night and so far he isnt being quite the jerk he was... I swear those little guys are trying to antagonise him though... they keep swimming up to him and then seem surprised when he chases them away lol. I'll prob get another 1 or even 2 if things get worse. As for the size issue, I dont know if there are any bigger ones, Ive never seen them for sale locally. I got these 3 delivered and the 1st one was bigger than advertised so i think he was the odd one out of the batch. Ill have to ask when i call to order. Thanks for the help guys...