From this time on his parents dedicated him to be a missionary doctor, "wrote Mrs. Landsborough David and Marjorie's dream for their son came true. David junior grew up to become a medical missionary, and even followed in his father's footsteps by returning to Changhua Christian Hospital, where he served for 28 years.
蘭大衛夫婦的願望果真實現，他的兒子蘭大弼日後不僅成為一名醫療宣教士，還「子承父業」在一九五二年回到彰化基督教醫院服務。