Hi twobone, I was diagnosed when I was 29 with chronic inflammatory arthritis (now 45). Long story short is that the new TNF blocking medications have done wonders for me. The drugs are usually administered through injection or IV. Basically they suppress your immune system to a certain degree in order to keep your body from attacking itself. Of course with all drugs there are pros and cons. Only your SIL and her physician can make the choice that is best for her.
I have been on Humira for about 7 years with no side effects to date. Prior to that I was on Enbrel for a few years. While the drugs minimize the effects and destruction of the disease, they do not eliminate all symptoms and "flare ups". I learned to live with the ebbs and flows so to speak. I posted about 18 months ago how well I was, challenging my fiance in P90X. Currently for the past 4 months I've dealt with constant chronic pain and various joints swelling, lucky to feel well enough to walk around a mall for a short time. But I'm optimistic enough to know that this too shall pass.
Watch the diet especially sugar and alcohol. Get LOTS of QUALITY sleep. There is a difference. I wish her luck and she is not alone...
