Complex sentence: From 1981 to 1983, Bil published the gag strip "Eggheads" in collaboration with his son Jeff, who currently serves as his father's assistant and is expected to take over daily production of "The Family Circus" when Bil retires.
Split into simpler sentences: From 1981 to 1983, Bil also published the gag strip "Eggheads" in collaboration with his son Jeff. Jeff currently acts as Bil's assistant and is expected to take over daily production of the strip when Bil retires.