Sometimes when I am too lazy to dig and separate bearded iris, I just go out with a knife and cut out the ones that I want to and leave the remaining iris less crowded. If you remove the rhizome and some of the roots, what is left in the ground doesn't make more plants. No digging, no cutting lines unless they are really near the surface. I don't see why the OP can't just do this, unless it is a Sib or something.