How long does the Man o' War stay with their parents?

Answer 1

A Man o' War is like a jellyfish, except that while the jellyfish is just one individual, the Man o' War is composed of a whole lot of individuals. They have 4 type of individuals living in the group: The floating sac, the tentacles, the gastros (digestion) and the gonos (reproduction.)

There are males and females . . . at a certain time of year, all the Men o' War males discharge sperm into the seawater, and the eggs of females of other groups are fertilized by them. So, to answer your question, the young Men o' War have nothing to do with their "parents" which are likely nowhere near, anyway.