Corey Griffin, CEO of The Boston Co. Asset Management, added the title of chairman while relinquishing the title of president. Ronald P. O'Hanley was chairman; he will retain his position as vice chairman of parent company Mellon Financial. Patrick Sheppard, COO of Mellon Institutional Asset Management, will replace Mr. Griffin as president; he also was named COO. The COO position, previously held by Mr. Griffin as well, had been open for a while, said spokesman Joseph F. Ailinger. No information was available on who will replace Mr. Sheppard at Mellon Institutional.