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I am having the same problem with my daylilies. I already donated gazillions to a school planting project (and THEY did the digging, hee!). Now I have another patch to clear, and am seeking another organization looking for free plants (the only cost is that they do the removal). Then I have to get rid of snow on the mountain and irises galore. Apparently I have a knack for choosing highly invasive perennials, LOL!

Johnson's Geranium (nice blue-to-pink flower) will eventually crowd out/kill Bishop's Weed. It may take awhile.

Iris: depends on if they are the common ones or the hybrids. Sedum and Bishop's weed will overgrow them and keep them from flowering, if they are hybrid. Hybrids need to be divided every couple of years. Common Iris need sun, so putting up shade cloth over them for a season or two might work. I have a small patch of them and they have spread slowly as Yellow Primrose takes over. They are in a semi-shaded area.

I have plantings that are reclaimed pig pasture (been over 30 years since any animals were there). I start with tilling and a couple of years of black plastic/particle board. Then I put in sedum.

The sedum grows and keeps out a lot of weeds. Then, in 2-3 years, I transplant the sedum to a new area and replace with whatever I think will survive and spread quickly. So far, my favorite for spreading and taking over is a pink bush hollyhock (sometimes it sends out a white plant). Nice glossy leaves and it grows to maybe 4 feet (hard to tell as all this area is hilly). In 3 years or so, the hollyhocks have taken over. I have no idea what this plant is called. I just got some seeds from my SIL.

Bear in mind that I am recovering several acres, a few feet at a time. I mulch heavily with wheat straw (6"-8") after every weeding. There are no seed heads in this straw and it really seems to keep the weeds out.I don't have the time for extensive weeding on a consistent basis.

Yellow Primrose is another nice spreader, IMO. It can hold it's own with sedum and eventually take over.

I inter-plant Red Monarda (Bee Balm) with the common Tiger lilies. They keep the Tiger lilies in check, bloom sometime during the lilies' bloom time and then are there after the lilies are done. The Monarda is spreading among the lilies, which are not spreading.