I too taught multiple children, but I was able to group them together for some levels because that is where their comprehension was. Eventually they all moved at a different pace and I now have 4 children in 4 different places. I started out with 5 but the oldest has since graduated.
My oldest two are now in Algebra and Geometry but there are times when they too need my help. My youngest is half way through The Geometric Approach and his older brother just finished it.
As to teaching multiple....I do what Rachel does....while working with one child I will have the other doing some kind of independent work... or chore...or something to keep them busy. Plus I try to combine them in other subjects like history and Bible which then frees up a little more time.
I have been homeschooling for 18 years now. I never did anything easy...I am a very teacher intensive type of person. Yes, my days can be long in comparison but I can say it's been worth it in the long run. I've had to sacrifice in other areas but it's really only for a season. Some years are more intense than others and as the children grow they do become able to do more work independently.
Test your children and if they test at the same level then try teaching them at that level together. But if not...and you have to teach them at different levels....it is possible. But it will take a commitment from you and maybe even from your husband. You may find you need to teach one or more their math when dad gets home to help with the other children.
Thanks for the replies. I am very interested in this program but was really hoping to combine at least to some extent. I failed to mention my older son, three year old daughter, and baby on the way. :) It's not as simple as amusing some while I work with others for one subject. :)