I completely symphatise with you, my husband is a CIDP sufferer since November last, he’s still in a wheelchair and he can use his hands just about. He’s had a few treatments ( IVIg, plasma exchange , cyclosporine and now prednisolone and azathioprine) but non of them gave results so far. He’s had a EMG not long ago and showed no deterioration or improvement since may. The docs suggested to stay on prednisolone and azathioprine for another month and see if gives any benefits( they say that azathioprine takes at least 3 months to give some improvements if any and he’s taken it for 2 months now). He’s been on prednisolone at 60 mg a day since march but with high doses of calcium every day , magnesium and zinc, plus alendronic acid 70 mg once a week , he’s bones are as good as they ware before. But my advice to you is stop prednisolone because all your father in law gets from it is the side effects and ask your docs for an alternative treatment ( Keith gave you a few suggestions ), lucky he hasn’t got any pain a pill of pregabalin( neuropathic painkiller) is over 1£ -thank God for NHS-.I feel a little bad seeing people fighting with the insurance company or with other institutes for drugs that they need to live on and most of it only because they haven’t been fortunate enough to be born in a different country or better say the politicians are not competent enough. The health institutes should be free , sorry you have to go thru all this trouble to get a supply of IVIg and good luck in the battle with CIDP.
I wish you and your family all the best in the world and you’ll be in my prayers.