Overweight Adult Cat + Five Month old Kitten

I have an overweight cat (Freyja) that needs to be on weight control dry food and a 5 month old kitten (Rory) who needs to be on kitten food. Any ideas on how to keep them from eating each others' food? Freyja doesn't like to jump up on the furniture, so I put Rory's food on the credenza. But, this has motivated Freyja to finally do some exploring to find his food, and Rory seems to be only interested in the weight control food. We keep the dry food out all day, and they also get a spoonful of wet food twice a day.

Other than keep them separated, feeding them on a schedule instead of free feeding, or putting the kitten's food in a room with the door closed just enough for him to get in but not the adult cat, I don't know that there is much you can do to keep them from eating each other's food.  I've seen a thread that mentioned putting food in a box with a magnetic lock that is unlocked by something on the cat's collar.

We switched all of our adult cats from dry to wet, and the two overweight cats have started losing weight, looking better and acting more spry/playing more.  A month ago, we fully integrated them into the entire house (instead of keeping them separated from the adults).  We switched our five month old kittens to the wet food that the adult cats eat.  We give the kittens a little more at each meal and feed them one more meal a day to make up the calories they need.

Thank you TX_Kat! How did you switch the cats over just to wet food? I guess that may be a little better for them, since they will get more water, and it's more like the food they would get from a hunt. Do you feed them like a half can a day?

I am hoping this would just be a temporary thing, until Rory is big enough to eat adult food. I sometimes need to work crazy hours, and prefer the dry food being out, in case the cats get hungry and I am not home to feed them.

That magnetic box sounds pretty cool, but I think a little more complicated that I need.

We started by feeding the correct amount of dry food at set times each day to get them used to not free-feeding.  Then we started with 1/3 of a 5.5 oz can for each cat twice a day, and left kibble to make up the calories when we went to work as we figured out what wet foods the cats would and wouldn't eat.  They hated pate and preferred Friskies filets and bits.  They didn't even like Weruva very much.  After a few weeks, they were eating 1/3 of a 5.5 oz can each 2-3 times a day.  There were some days that we had to crush dry food on top of the wet food like sprinkles on ice cream to entice them to eat the wet, and there were some days that they just wouldn't eat wet at all and only ate kibble. 

The kittens have eaten the same food as the adults for the past two months.  Up until a month ago, we isolated them in their room at night and let them free-feed on kibble.  Now that they are completely integrated with the adults, they are fed with the adult cats, just a little more at each meal to give them all the calories they need.  The typically get 1/2 a 5.5 oz can or so at each meal, and would eat more if we would let them.

I understand crazy schedules. My husband and I both work nights (him 10 hours, me 12 hours).  I'm of the opinion now that going 12 hours or so isn't going to kill any of the cats or kittens, and them being a little hungry might actually be good for them.  In the four months since we started switching the cats from dry to wet, our obese cat has lost 2.4#.  All of the cats' coats are shinier, and the all of the cats are more playful and spry. 

I try to feed my cats in separate rooms, so I can monitor how much each kitty eats. I think tx_kat has given some awesome advice already though. A switch to wet food would be optimal.