Getting a cat off Friskies canned?

We(my roommates and I) have 3 cats ages 3, 3, and 14. We have an autofeeder to feed dry food 3 times a day and successfully switched them from iams dry to wellness core indoor dry. One of the three year old cats however prefers canned food. He has been on friskies canned most of his life however we have noticed recently that he seems to be loosing weight. The cats all are more stressed out right now because we got a puppy a few months ago and we are still working on training her to leave the cats alone. They have 2 safe rooms in the house to get away from the puppy, but they still aren't happy that there is a 50lb puppy that gets excited whenever she can see them. I thought switching to a healthier food would help him, but after 1 or 2 meals he rejects anything good and won't eat again until he is given friskies and won't eat anything else for a week or so.  I was really hoping he would like the wellness canned so we could buy the 12oz cans to save money and get it autoshipped with our dog food but it doesn't look like that is going to work out. The other 3 year old cat prefers the dry food and only wants canned a few times a month, however the 14 year old cat seems to love the wellness canned and comes around for dinner more often after we tried to start feeding it. Should I try mixing the friskies with the wellness? Is there some kind of supplements we can give him with the friskies to get him more nutrients? Thanks.
 

Oh and on occasion he will reject the friskies and we have fed fancy feast(not the classic though, for some reason he won't eat the fancy feast pate flavors) for a few days before he goes back to wanting friskies. I swear I've never met a pickier cat, lol. In my mind this is like someone rejecting a steak dinner and wanting hamburger helper instead. I am at a loss here. I am going to suggest we start weighing him every other day though to monitor his weight loss and make sure he doesn't need a visit to the vet if its something other than stress.

Okay, I prefer feeding my kitties canned food myself. It is high in moisture for them. I feed Friskies canned and 9lives. I do not think it would do him any harm if he stayed on the canned Friskies. It is not as bad with the by-products as they are made to be, think of it this way, if they were to eat a mouse they eat all of it. Please do not let him not eat anything for a week, trying to move him over to dry. It is much better he ate something than nothing at all.Very bad if he doesn't eat at all. I buy the 13oz cans of Friskies pate at Dollar Tree. I think it may be stress that is causing him to lose weight, firstly, the new dog and then the new food, it is a lot for him to deal with. By any chance can you keep the puppy in a room by herself and let the cats smell under the door and gradually get to know one another? Always keep the puppy leashed or crated when around the kitties until you are certain they get along, another thing, please never leave them alone together, a dog that size, may accidentally hurt one kitty.

We always put him back on friskies after he refuses 2-3 meals of anything else. He will eat a few kibbles here and there but would probably murder us in our sleep if we didn't give him his canned food, lol. He doesn't like being held very often so its hard to really tell how much weight he has lost but about 2 weeks ago is when we noticed that he seemed lighter. We are working with a profession trainer with the puppy(who was 2 months when we got her and is now 6 months old) and she does stayed leashed at all times when not in her crate. When we first brought her home(and she was smaller) we tried letting the cats smell her through the crate over several days but they are not at all interested in having anything to do with her. Even at night when the puppy is sleeping they don't want to investigate the crate with the puppy in it. The older cat is more used to dogs and has the "i'm too old to deal with you, leave me alone attitude" and will tell the puppy to leave her alone and the puppy listens. The 2 younger cats however won't do anything, so we use the leash to keep the puppy away from them when they venture into the room with the puppy. At this point the puppy is never left uncrated when we are not home because we know she can't be trusted to not eat the house. The cats have the run of the house during the day and after bedtime. And anytime the puppy is out the cats prefer to stay in one of the safe rooms(the 2 largest rooms in the house that stay blocked off and the puppy is never allowed in there)

Also we tried the blanket switching. Taking a blanket the cats use and switching it back and forth with one the puppy uses to try and get them used to each others scents. But the cats really could care less. I have talked with others that have introduced large puppies into households with cats and have been told that it can take up to a year for them to get along...really just until the puppy is older and not so energetic.

Seems like you're doing really everything pretty well. I am wondering though, with three cats in the house, can you possibly tell if there has been any change in litterbox visits?

No we wouldn't be able to tell. We have one indoor litter box and one outdoor. We have a cat fence system in place so that the cats have access to the backyard and the male cat prefers using the yard over the litter boxes anyways.