One line family tree

I have been asked to produce a Tree that consists of one line of Ancestors and Descendents from my Master List on Ancestry.
I want to download my Ancest6ry Master Tree to Roots Magic 8 and then produce a unique Tree (Gedcom) deleting everyone except a particular man and woman, their siblings, children and ancestors on both sides.
Is there an easy way to do this?
TIA

Ron