The Magna Carta base camp states that "Please pick one that is ready to get started before working on additional trails for a favorite Gateway Ancestor!"
I believe the idea is that the gateway ancestors usually have several Magna Carta Surety Barons that they are descended from. As we badge more and more profiles and they begin to intersect, the end result is becoming that we end up with gateway ancestors in multiple lines already. Once a gateway ancestor has a badged line--we move to the next gateway ancestor. In theory, you could continue researching a line, but with limited group member establishing and reviewing lines, it wouldn't be practical. On the other hand, Liz or one of the other group leaders would probably have the most concise response. : )