In a block-selective solvent for the B and D blocks of two diblock copolymers B-C and C-D, both diblocks should form micelles. Normally chains of the different diblocks do not mix significantly or comicellize for repulsion between the B and D coronal chains. This paper describes the tagging of the C blocks by adenine (A) and thymine (T), a H-bonding nucleic acid pair, to enhance mixing of the different diblock chains in a micelle. This enhancement effect has been observed in the premixed micelles prepared by first mixing the two diblocks in a solvent good for all of the three blocks and then adding a block-selective solvent for B and D. The A and T tagging has been shown also to enhance mixing of chains of different diblocks among the premade or the initially pure B-C and C-D micelles. While the A and T tagging helped give mixed micelles or micelles consisting of chains of both diblocks, the intrinsic repulsion between the B and D chains made them segregate into interesting patterns, including being two-faced and flowerlike in the coronas of the mixed premade micelles. Mixed micelles with surface-segregated chains may have intriguing applications.