I have a list of organizations in 2 columns - parent in column A, child in column B.

It could look like this:
A B
B C
B D
C E
D F
F G
and so on.

Is there an easy-ish way to convert this to a list of unique branches? Where the result would look like:
A B
A B C
A B C E
A B D
A B D F
A B D F G

Any thoughts?