Chapter-name wise, I think you did an apt name as it's trying to refer to how our interactions change the world, but sime other options (that kinda sound lame in my head,
Grandpa and the butterfly effect,
Grandpa and consequences of existence,
Grandpa actions and reaction of existence (too long),
Grandpa and the ripples of life,
Grandpa and causality, etc...
From the names I listed, i think what you chose fits the best.
Thought of another, Grandpa and the ripples through causality