It's not a good idea to split rhizomes the first year. Initial growth is dependent on the energy stored in the rhizome and if you split one, you have as good a chance to have two deaders as two plants. Next Spring, you can dig up all the rhizomes you desire. I just wait until there are shoots a few feet from the original plant, then cut the root and move the shoot.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk