(Click for bigger version and all.)
It have started to bug me that it is impossible to keep track of how people are related in the Outlander books, and adding a bit of time travelling doesn't make the tree itself any straighter. The blue rectangle is simply there because it seemed like a good idea to indicate that it was the same people, although in different times.
As I worked with this I realised Roger and Brianna would never have met if they both stayed in the time they were conceived (1745 and ca. 1940.) Even if Jamie had fathered Brianna at the age of ninety and herself had grown to be close to a hundred, we're only reacing a bit before the first World War, with luck! And that's containing a lot of 'what if's and 'maybe's.
To get Morag to line up with being Roger's six-times great grandmother I assumed a new generation to lead the line would appear every twenty-fifth year, and still it doesn't line up completely.
All I all I have concluded Jamie to be Roger's first cousin, seven times removed, in addition to his father-in-law, of course. Brianna is then Roger's second cousin, six times removed. In turn, Jemmy would have to be third cousin, six times removed with his own father, seen from his mother's side, and the same reversed to his mother, seen from his father's side. To add to the tangle: He's his own fourth cousin, seven (?) times removed. His grandfather, Jamie, is also his first cousin, eight times removed. Dougal is pretty straight forward his great-great-great-great-great-great-grea
I refuse to think of how Young Ian and co. fits into that.
I might have got some of that wrong, to be honest, but you can see how it lines up for yourself.