Question about debth of TB Iris from last year.

I really am very new to TB iris. I planted last year, they bloomed this year and everything went very well. So I know that when you plant you make sure the rhizomes are not too deep and tops are exposed. I must have done it right as mine grew and multiplied like bunnies and bloomed great this spring.

Now what I am noticeing is that the iris rhizomes off the mother (fading) rhizomes are ending up deeper in ground than than the original I planted last year. This seems to be because of the way they grow were the babies come out of the sides of the mother but from near the bottom. They look to me to end up much deeper than the ones I planted myself. That with the fact that the old iris leaves shrivel up and die and end up pretty much on top of them and I wonder if they get the sunlight I read that rhizomes must have.

take away the old shriveled up , brown, or dead straps, leave babies attached to Mom for at least another season, right where they are....... maybe divide and replant in the 3rd year if they are crowded