First, I would post a detailed list of your benefits package. This package should include 100% fully paid for health insurance that requires zero additional money from the employee except for perhaps prescription co-pays (not to exceed $20/ea or something).
You should also have a generous time off package and generous/unlimited sick days allowance. In Europe, this is already the norm. If I'm sick for 2 weeks in bed, I still would get paid. Obviously I need a doctor's note after a 2 or 3 days, but that shouldn't be an issue if they really are that ill.
Finally, really take a hard look at your expectations for when work will be completed. If you have a team of 10 devs and 2 of them really only work on average 10 months a year due to their disability, can you justify that to management and still meet your deadlines? Preferably, you work in a field where the deadlines are all made up and you can build in generous buffers.
This is true in industries like gamedev already. The game is sometimes done months in advance of the launch (or should be, ideally) and then marketing takes over while the team transitions to writing DLC or working on the next project.
It's laudable that you'd want to take on hiring people with disabilities but you must be realistic with what you are getting yourself into, especially if those disabilities are chronic in nature and require frequent visits to a doctor.
In return for providing all of these benefits, you will gain some of the most loyal, hardworking, and compassionate team members and all around great human beings. I have friends with such disabilities and it's not a secret who the good companies are to work for. By providing excellent benefits like these, you'll also attract a lot of other great talent and perhaps make new business partnerships because of the network influence of your engineering team. It's well worth it, in my opinion.