Do you talk about something like "this is my grandfather, he descends from napoleon"?
Well you could declare Napoleon to be his father and put the correct years in Napoleon's data. Only you would not get something like a longer dashed line in another color to connect the two! You could try to put an "ancestor" in between, and make his gender 'Other' and try a name such as "5 generations"....
If you want to achieve something DIFFERENT, pleae clarify!
PS: many sytems will give warnings like "Possible ERROR", as far as I know FamilyEcho will not.