She will have you making amazing and delicious goodies.
Also this website: http://yourlighterside.com/. This is the woman who invented cauliflower pizza crust and she's brilliant.
Of course, you can also go to the Atkins site. (Keto is Atkins): https://www.atkins.com/

It is a starch, so not sure how it fits into a keto scheme, but I've read to use 1/3 to 1/2 the amount of corn starch.

and made substitutions. I used almond flour instead of wheat flour and Splenda instead of sugar. They came out great! My husband brought home some dark chocolate, Stevia-sweetened chips and those were good, too, although I prefer the semi-sweet chips. Last night I tried making pizza crust with the King Arthur almond flour recipe and it was horrid. Yuck. Some things just don't substitute well.

....I've lost 50 lbs, and nearly at my goal weight. This isn't a diet to me, but a way of life, what keto people call WOE; Way of Eating. Here's a few things I've learned, in no particular order:

1. Don't try to swap almond flour straight across for wheat flour. It won't work. Find a good keto cookbook. I agree that Carolyn Ketcham is the best. Go to her website, and you can order the book from Amazon. Her duck fat chocolate chip cookies are great.

2. Don't use coconut flour and almond flour interchangeably. Coconut flour absorbs a lot of liquid, so you have to adjust liquids accordingly. Most recipes will use predominately almond flour, with a small amount of coconut.

3. You want pizza? I recommend Fat Head, it's made with Mozzarella cheese and almond flour. Recipes are all over keto websites. When the cheese melts, it takes on a bread-like consistency.

4. Make sure you get finely ground almond flour. The meal is too thick and coarse for cookies. Could be that's why yours were crumbly.

5. Get a product called "Thick-it-Up" for thickening gravy and sauces. Available from Amazon. Also Anthony's almond flour, coconut flour and cocoa powder, also at Amazon. Besides Thick-it-up, you can also use heavy whipping cream as a low carb thickener.

6. The best sweeteners I've tried are Erythritol, brand name Swerve, and Stevia. But Stevia can be bitter if you put in too much. Together, with Erythritol, they seem to balance each other.

There's more, but that's the basics. Bless you for trying to help your SIL stay on her eating plan. Let me know if I can be of any help or answer any questions.