Melinda French Gates will have to resign as co-chair and trustee of the Gates Foundation in two years if she and Bill Gates can’t work together. “They have agreed that if after two years either one of them decides that they cannot continue to work together, Melinda will resign as co-chair and trustee,” the foundation’s chief executive, Mark Suzman, told employees Wednesday. French Gates would then “receive personal resources from Bill for her philanthropic work,” he added. The foundation also plans to expand its board to those outside the family’s inner circle, something experts and former foundation employees have called for in the past. “Given that founders receive a substantial tax benefit for their donations, the assets the board oversees should be regarded as belonging to the public,” Alex Friedman, the foundation’s former chief financial officer, and Julie Sunderland, its former director of Strategic Investment Fund, wrote after news of the couple’s split. Because of the Gates’ “hands-on leadership” style, change will take time, Suzman cautioned. “So we’ll need some time to think through how we balance that with the people we bring on board,” he said.