(Portland, OR)  --  Two law firms, one from Portland and one from Seattle, are merging.  Portland's Miller Nash is uniting with Seattle's Graham & Dunn, to form the Miller Nash Graham & Dunn law firm.  SeattlePI.com reports the combination will place 160 attorneys under one umbrella and form what's being described as a new Northwest powerhouse corporate law firm.  The merger was approved yesterday by equity partners of both firms, and will become effective January 1st.