Welcome to IHD!
Often Kids will be scared when a Parent has to have medical treatments. Worried that Mom could easily die. This can be quite traumatic. Kids today are much smarter than past generations. They learn so much more and so much quicker, they can understand if things are spelled out clear enough.
Kidney School is a great web site to learn about the kidneys, what they do, how, what goes wrong, and how the different types of dialysis can be used to treat the person, keeping them alive and well. Diet is very important, and this is also spelled out.
http://kidneyschool.org/Explain what is going on, suggest the kids spend a little time studying at Kidney school. They will quickly lose their fears and understand exactly what and why Mom has to take care of herself doing PD.
Take Care,
Charlie B53