A dramatic expansion happens between 1750 and 1800 as the map flourishes with new connections. The Babbs have cemented themselves throughout Devon, but a few things have not changed. The appearance that these are all descendants of the same tree. It may have been splintered into new genetic combinations over time as closely held family secrets come to light.
But to be honest, only two cases of infidelity over an almost 350-year period is a stunning feat! I know individuals who have personally surpassed that number.