How much information gets overridden when you do a merge?
I did get (great) help on a similar issue recently, but I want to be sure I understood this part:
Say I have "Jane Doe 1" in my branch, with carefully researched and attached spouse, kids, siblings and forebears... and then I find an existing duplicate "Jane Doe 2" in the tree, who also has profiles for the corresponding spouse/kids/forebears attached. If I merge mine into Jane Doe 2, will her existing family branch replace/override what I already have, going back through all the generations?
(A related question: do the two sets of sources combine as well?)