Cat got addicted to ProPlan...what should I do?

My 14 year old cat has been on a blend of Orijen and Acana(because Orijen is too rich on its own, but it offers a greater variety of nutrient sources than Acana) for years, but after a recent illness I wanted to boost her calorie intake a bit to help her gain weight. I was going to add a few Evo kibbles to her meals, but couldn't find that anywhere. So I found a nice big pet store and started reading bags until I found something with okay ingredients that had higher calories than what she was on already. That ended up being Purina ProPlan Kitten food. I replaced about 1/3 of each meal with this. This got my kitty eating very well and gaining weight at a decent rate, not too fast. She's doing great, but I'm having trouble getting her to eat her old food now! She picks out all the ProPlan kibbles first and barely touches the rest. I have been burying the ProPlan under her normal blend to trick her into eating both, but there's always Orijen/Acana kibbles left afterwards. Sometimes almost half her meal is still around by the time I give her the next one! Today she ate all the ProPlan from her dish and then sat there meowing at me for more. When I drew her attention to the food left in the dish, she pushed it off the shelf and continued meowing!(PJ's food dish is up on a shelf so that the kitten can't get at it, but PJ doesn't have any trouble jumping up) I cleaned up the mess and put the food back in front of her but she just sits there expecting me to bring ProPlan.

I'm thinking about putting her on 100% ProPlan for a while, and then reintroducing the original blend to make it seem new and interesting. Any thoughts on this? I worry about my kitty getting sick from such a diet after being accustomed to Orijen. I'm also not sure it'll work, because it seems like Purina uses some magic ingredient that turns their food into crack for cats.

On a side note, I just discovered that Orijen's fish are wild caught. Wouldn't this be a health concern? I'm not worried about the free range herbivores, because they're pretty low on the food chain, but wild fish can build up quite a lot of toxins. I normally go for the 6 fish formula, because all the oils from the fish prevent hairballs(she's long hair), but I might reconsider this choice considering the fish are wild...

Have you thought about powdering up the Pro Plan and just sprinkling it over her other food?  That way there would be the taste of it throughout the bowl, yet she wouldn't be able to pick out specific pieces.  It might work, although it might not.  Better yet, have you thought about putting both of them on canned food?  Then you could use the ProPlan (crushed) as a topper to get them converted to canned. 

As far as Orijen using wild caught fish vs farm raised, I would, personally, always eat wild caught before eating farm raised.  But if you're  concerned, buy a different protein and use Salmon Oil or Krill Oil or Anchovy Oil or something like that

Unfortunately, PJ hates canned food. She likes the cheap packets with the gravy in them, but mostly just for the gravy. She won't eat pate at all. If I give her a gravy type food, she'll eat some of the meat too if it's small enough to pick up accidentally while licking gravy. I just can't get enough food into her with canned stuff. But she drinks plenty and she's always done great on dry food(in all her 14 years, she was never sick until after her recent dental work) so I'm happy giving her the best dry food I can.

I'll try powdering the ProPlan tomorrow. Maybe that way I can slowly wean her off the taste of it and get her back onto her healthier diet sooner.

Do we have the same cat?  She only likes the gravy.

Yeah, that's why I only give her moist food as a treat.

Anyway, the powder method failed! It was a good idea, though! PJ ate a few kibble and then decided it was a trick.