Q.Planting siberan. Iris
What is the bst way to plant the rhizome with roots. Should the rhizomes,be vovered with soul? How deep and can several be planted togeter as daffodil bulbs

Cover the rhizomes with 2 to 3 inches of soil and space them about 2 feet apart.
This allows enough space for the iris to spread.
I would plant your Daffodils near the Iris but don't plant them directly next to each other.
You will need to lift and divide both the Iris and Daffodils at times and if they are planted separately, this task will be much easier.
https://www.gardeningknowhow.com/ornamental/bulbs/iris/growing-siberian-iris.htm
https://www.gardeningknowhow.com/ornamental/bulbs/daffodil/daffodil-planting-care-tips-how-to-plant-daffodils-in-your-garden.htm