By Monica E. Oss When executives of health and human service organizations have made the strategic decision that they need a "partner" (see Thinking Of MA&A? What Should You Be Thinking About?, M&A To Build Scale & Market Diversity: A Q&A With David Guth, Centerstone and 10 Keys To A Successful Merger & Acquisition Strategy), the question is-what's next? The decisions that need to be made are what kind of "partnership" and what "partner." Over the past two years, we've written about a wide range of collaborations. From mergers and acquisitions, to affiliations, to administrative services organizations, to formal partnerships, to joint ventures, to…