new cats to the house

I have two cats, Monty and Wilma who weigh 14 and 16 pounds. Both of my cats are declawed and fixed and have always been indoor cats. I got married and moved in with my wife and her 2 daughters and their 3 cats about a month and a half ago. Since then, my cats have been hiding under my stepdaughter's bed, only coming out once in a while. Monty has lost half his body weight and neither one of them is eating. I am VERY worried about both of them. I am very close to them and am constantly worried that if they continue on this trend, they may not make it. Two of my wife's cats leave mine alone, but one of them, the alpah-male, will intimidate them, so they hide. I have been trying keep them out of the bedroom so they can't hide under the bed, but I haven't seen any improvement. Someone please help, I don't want my kitties to die or feel sick. What do I do???

Keep them separated for now and read the 'Introducing..." thread at the top of the forum. They know they're 'invaders' and are reacting appropriately, but there are ways to deal with it so that all end up happy and your cats healthy.