We call our own mother "mum". What should we call our mother-in-law? In China, we call our mother-in-law "mum" as well. Do English speaking people feel comfortable calling their mother-in-law "mum"? Could we simply call our mother-in-law by her first name?
EDIT: I thought it was just about everyday conversation and not about complicated cultural practice. To be clear, I'm not asking what to call mother-in-laws in different cultures. Rather, I just want to know what native people in countries like U.S., U.K., Australia, Canada and New Zealand call their mother-in-law in daily conversation.