Hi Dar:  This is a great and complex question that should be answered by the Dr that is prescribing these meds.  It sounds like you've done a good job researching these meds and their possible interaction, so take this knowledge and your wonderful insight to your physician and ask which might be better, Actonel or Fosamax, for your given medical situation.   Both Actonel and Fosamax *may* cause GI problems so you need a educated answer from someone that understands this possibility, and the most likely place to get that would be your Dr as well as a trusted and knowledgeable Pharmacist.   It must be difficult to deal with all of these challenges, but it also sounds like that's exactly what you are doing.  Continue to educate yourself, it will help in making these decisions and advocating for yourself.   If you are seeing an Endocrinologist for the Levoyl and prednisone, this Dr should be able to tell you if these med are contraindicated with osteo meds.  If you aren't seeing an Endo, that's ok too, the Dr prescibing these meds plus your pharmacist should be able to look all of this up to see if any of these treatments interact with one another.  Long term prednisone use *may* cause osteoporosis, but if you are taking this for a condition that must be treated, like chronic lung problems, you have to understand the importance of that, since you have to be able to breath.   Good luck with your decision and all your medical issues, I wish you the best.  Keep up the good work on your research of these matters.