It has been my thought for a long time that this is the case, but I am unsure currently, since the parasympathetic tract of colon sigmoideum does not seem to have connection with CN 10. It connects with pelvic splanchnic nerves. Discussion about it here.
If there is no connection from pelvic splanchnic nerves to CN 10, like CN 10 running within the nerves, then my though must be wrong.
Are CN3, CN7, CN9 and CN10 the only Parasympathetic Cranial Nerves?