As a fan of time travel fictions (or not fiction, who know), always been interested in Temporal Grandfather paradox... As if you are so wicked to kill your grandfather when going back to the fifties, then what happens to the poor you (See Back to the Future, the heroe is disolving when Mum suddendly ignores Dad at the Prom night)
Well, Travelers series stay logical, even they alter the course of the future. Why? Because they are spirits in host bodies.
So even they change the future, and the one of their host's childen, because they are spirits with no ties with the host body, then, not Grand father paradox