I'm just finishing grad school now, so I have recent experience in the college world.
First of all, I would suggest talking to your sons' school about their services for students with disabilities. My school has a great program with lots of options.
Secondly, depending on your circumstances, I would consider having your sons take less credits next semester. That was never an option for me because I needed to be a full time student to stay on my parent's health insurance, but it's something to think about. If they can't drop some credits next semester, help them to plan their schedule to spread the hard courses out. I tried as hard as possible to only have one or two classes that were really challenging at a time. As sophomores, they're likely still taking some gen ed requirements, so carefully select the course they take for that. I used ratemyprofessor.com to help me choose which professors I took classes with. Often, a professor makes or breaks the difficulty of the course.
You may want to look into summer courses, as well. If there is a class that is particularly challenging and is offered over the summer, have your sons take it now. Only having one course to worry about will allow them to focus their energy on doing well rather than meeting lots of different requirements.
It may benefit them to do some research on how to study. I know some schools offer courses, but you can find lots of info online, as well. Transitioning from high school (where much of the info is handed to the student) to college (where learning is largely independent) is challenging. There are lots of learning styles, and figuring out what works best for your self individually is key to success.
Make sure your sons are taking advantage of office hours. The professors will give your sons studying tips (for example, which info to focus on), help your sons organize their learning, support missing information, etc. Also, professors are much more understanding of students who struggle but show the effort, than students who are struggling but never come for help.
I've known lots of people who have struggled freshman year and then turned it around. This transition is hard! It takes some time to really understand how to be successful in college. In fact, I'm finishing my fifth year in higher education, and I'm still learning how to be a good college student
It will all work out! It just takes some planning and hard work!