How to Use Soapwort

I recently received a very helpful answer from you regarding growing herbs in containers, for which I thank you. Among others, I placed an order to buy a soapwort plant from Richters, and my question concerns the appropriate way to make "soap" from it. I read conflicting information from different sources – some say to boil the dried roots, others to boil stems and leaves. Which one is the appropriate way? Could you also indicate to me what ratio I should have of plant material and water? Can other plants be added, such as chamomile or mint? If leaves and stems are to be used, can they be used either dried or fresh?

According to Margaret Dinsdale, author of "Skin Deep", an excellent book on making your own herbal body products, both the leaves and roots are used. The fresh leaves infused in boiling water makes a mild soap substitute. But it is my impression is that the roots are richer in saponins, the constituents that are responsible for the soapy nature of the plant.
The "Plants for a Future" database (https://www.ibiblio.org/pfaf/cgi-bin/arr_html?Saponaria+officinalis&CAN=LATIND) says this about soapwort [sans references]:
"A soap can be obtained by boiling the whole plant (but especially the root) in water. It is a gentle effective cleaner, used especially on delicate fabrics that can be harmed by modern synthetic soaps (it has been used to clean the Bayeaux tapestry). It effects a lustre in the fabric. The best soap is obtained by infusing the plant in warm water. The roots can be dried and stored for later use. The plant is sometimes recommended as a hair shampoo, though it can cause eye irritations."
I could not find directions for making soap products with soapwort, but 100 grams of dried root in 1 liter of boiling water should work. Or add more roots as long as the mixture can be boiled. You may need to experiment to find the best ratio of dried roots to water depending on the product you are making.