Who is my employer?

I take care my mentally challange twin daughters. I am paid through IHSS. Social security and medicare is not deducted from my pay. the reason I was given, is because my daughters is my employer. How do I pay into social security and medicare. According to what I have read in your guide lines . How can they qualify to be my employer, because they can not give me direction on what to. I decides what their needs are and do it.