Jim has always travelled a lot. In fact, he was only two years old when he first flew to Madrid. His mother is German and his father is French. Jim was born in England, but his parents met/had met in Lisboa, Portugal after they had been living there for five years. They met one day while Jim's father was having lunch at a restaurant and his mother sat down next to him. Anyway, Jim travels a lot because his parents also travels a lot.
Would it be possible to choose met instead had met? First I thought it would not be possible because the meeting happened before the birth but now after thinking it over I'm not too sure. Because of the context, it seems obvious that the birth was a long time after the meeting and the clause with after use the past perfect progressive but it is true that both event are on the same time frame so may be "had met" is better