Cut peppers into quarters. Remove and discard stems and seeds. In a small bowl, mix cream cheese, blue cheese, bacon and green onion until blended., Grill peppers, covered, over medium-high heat or broil 4 in. from heat until slightly charred, 2-3 minutes on each side., Remove peppers from grill; fill each with about 1 tablespoon cheese mixture. Grill until cheese is melted, 2-3 minutes longer.