I suggest that she see a dietician, if possible, who can work with her.

If she has sweet cravings, she needs to go on metformin or find a suitable substitute. There are days where all I can think about is having a treat. Like last Saturday, I had a dream about a chocolate iced donut and woke up wanting one (so ridiculous, I know). I'm not going to lie, I totally had a chocolate iced donut that day and it was glorious.

If she can consume a treat in a controlled manner every week, then great! She might try substituting certain things for others. Many women with PCOS have varied carb cravings so for example, if she's craving french fries, maybe she could have half a baked sweet potato with a sprinkle of cinnamon instead (don't add brown sugar or marshmallows). For me, I will take a yukon gold potato and cut it up, drizzle it with some olive oil and bake it. I mean, it's not the greatest 400 calories but it's better than 600+ calories of french fries from a local fast food joint.

She could look into having frozen yogurt or low sugar ice cream (?) instead of ice cream. Or puree a frozen banana. Even though both of those options are carb rich, they might be less than ice cream. I don't know the nutrition information on either of those. Another option is to create coconut+dark chocolate fat bombs which are popular with keto people. She might also try eating a berry smoothie with ice and unsweetened almond milk instead of ice cream. Or maybe she buys a small one-serving container of ice cream!

I try to stay between 40-60 net carbs everyday. Some days I fail at that but in general, I think I'm doing okay. One thing worth noting, when I say something is so off limits, then I want it even more. Knowing when to balance saying no to that treat and when to allow yourself that treat is hard for me. If she can eat lower GI 90% of the time, I'd say she's doing pretty good. Again, please consult a dietician.