DALLAS — A partnership between a subsidiary of locally based investment firm CAF Cos. and Goldman Sachs Asset Management has acquired a portfolio of 16 multifamily properties totaling 2,766 units in Dallas-Fort Worth. The names and addresses of the properties, which are collectively known as The Obsidian Portfolio, were not disclosed, but all were constructed as market-rate projects. The new ownership plans to self-impose rent restrictions and social programming for renters at a variety of income levels. New services will include childcare, afterschool tutoring, workforce development and financial literacy. The seller was not disclosed.