Older cat feeding problems

Hi there. I have two cats: Penny, 13, and Violet, 2. Penny has always been a good eater. She has thrown up in the past, but I found Orijen the other year, and she loved it. So did my other cat Violet. We have been doing really well, but this spring, Penny started to lose weight. I started to monitor her food intake, and slowly, she has started to eat less and less of the dry food. When I do put it in front of her, she will sometimes eat it, but then she often gets sick right away.

That all being said, if I pop open a can of Fancy Feast, she comes running and she doesn't get sick. I only feed it to them as a once in a while treat. I need a new strategy. I want Penny to eat, but I don't think Fancy Feast is the best route. Any suggestions on what wet food to start with and how much for her. She is down to 9 pounds.

Plus I have Violet. She likes Origen. How do I feed them differently?

Have you taken Penny in for her senior bloodwork? I would rule out any medical problems first.

Does she eat slowly or fast? If she eats only a few bites but really fast, that could cause her to throw up. Have you tried feeding her only 5 or less kibbles at a time? That's what I have to do to get my dad's 14+ cat to eat properly.

Also, was Penny overweight before? 9 lbs is usually a good weight for a female cat.