Blended family fairness?

I am a part of a blended family, I have 2 children from my previous marriage (teenagers) and 1 from my current marriage,my partner has 4 from his first marriage. my children from my first marriage are very lucky, they attend private school, have all the modern gadgets (like laptops,ipods,psp etc). They are popular with there school peers,well spoken and achieve good grades. They are also very confident within themselves. They reside between there father and me due to good communication with my exhusband. My current partners children are not so lucky. They attend public school, and are just very average children, with not great self esteem and can be quite at times. The problem is because of my children's luck in life my current partner is continually putting them down and telling them how selfish and unfair they are to his children. He looks for excuses to argue with them. Help?