Marlborough (Mass.) Contributory Retirement System wants to add an active international growth equity strategy and is seeking a commingled fund manager to run from $6 million to $10 million in the strategy, confirmed Margaret Shea, plan director. Officials at the $90 million fund want to complement the existing international value portfolio managed by Boston Co. Asset Management for diversification, Ms. Shea said. Funding will likely come from reducing the $15 million Boston Co. portfolio. Plan officials hope to make a manager selection by September. Meketa Investment Group is assisting.