There are a few simple 'tricks' i can point off from the start that may help you notice gradual weightloss. They're not so much tricks as small steps toward becoming healthier and thus reducing calorie in-take at the same time. Dieting is not easy, it requires a lot of determination and a lot of knowledge about the foods you're actually eating. It also requires that you know where you are at in terms of how many minimum calories you need to sustain yourself (which can probably given to you with a hospital check up). Without working a complete dieting routine, it won't stick. There are a few changes which I can recommend right off the bat for editing your diet minorly though that helped me burn weight off back when i was trying to lose pounds too.
Step 1) Cut out any sugary drinks for water. Juice is acceptable, but not more than 1-2 cups a day, and preferbly get the 50% less sugar drinks if they are available to you. Ideally, you want to stray away completely from any non-diet soda, and limit the intake of diet sodas to a very minimal amount and/or completely cut it out with water. You may or may not drink soda or sugary drinks, but sticking to something like this immediately cut me 15-20 pounds when i was at a similar weight level as you, over the course of a year without any additional excercise. Cutting out alcohol from your diet would also be extremely helpful.
2) Steer away from greasy foods. Studies show that whole food's (mainly vegetables) give you a much more filling feeling compared to meats, and even more so compared to oils. Many fast foods load their foods with oils, creating 800 calorie meals that feel almost like nothing because the receptors in your stomach which signify you're full, do not detect calorie dense oils very well. This is a bit of a harder change especially if you are avid meat-eaters. For now, stick with low-fat white meats if possible, occasional redmeat is fine, but order something of higher quality like a small sirloin versus a burger patty.
I think these two changes alone would help your wife alot on her way down to 280, so her condition restraining her feet would be lessened. As for excercise, since I've been running for the last 2 years, I can't really remember what else I used to do before then. But I can say that doing the 2 above things made me gradually lose weight, without much effort (but of course over a longer course of time).
Great job on the weight loss so far! I gave birth a year ago and was overweight before getting pregnant, since giving birth I would say my 70+ pound weight loss was 80% diet and 20% exercise. Now that I'm about average in weight I plan on doing Insanity to start toning. I had to switch it up to different diets to sort of jump start it, I really loved making green smoothies. I would mix in kale, spinach, pecans, celery, flaxseed, and a fruit to give it flavor. I usually had this for breakfast and sometimes lunch. I would drink a lot of tea and green tea before dinner, I used Stevia to sweeten it, and drinking about about a gallon or more of water. For my exercise I would bike about an hour on an exercise bike while playing my 360. Good luck with the weight loss and trying to conceive.
I really would suggest doing alot of cardio, and try to lessen food intake. Try a 5 meals a day routine:
8am light breakfast, ie. 1/2 egg whites and 1 glass of milk, 250 grams of high fibre cereal with milk.
10am 3-5 pcs of biscuits/crackers.
12pm light lunch, ie. one half cup of rice, a little piece of steak, and more veggies.
3pm fruit time, 2pcs of banana/1 pc of apple/orange.
5pm light supper. just like lunch but i suggest mix it up a bit.
Definitely no buffet style meal/softdrinks/sweet drinks. Once a month cheat day. Cheat day should also be controlled.
I've been doing this and lose 20 pounds in a month. Good luck