What to call a mother-in-law?

Question

If a mother-in-law wants a warm relationship with her son's wife, what would she invite her daughter-in-law to call her, rather than "Senora"?
Thanks in advance
Daphne

PS I am writing a romantic novel with a Venezuelan hero. If anyone would like to open a private correspondence and help me with a few Spanish words and phrases, I'd be very grateful. Dictionaries and phrase books can't do it all!

Answer 1

Thank you Lazarus. I'm guessing a mother is "madre" is when you speak about your mother, and "mama" when you speak to her? (Can't do the accent marks in my program).
Daphne

Answer 2

The proper term is "suegra", but you wouldn't call your mother in law -face to face- like that. All depends on how close you are to her, or how formal she is. My mother in law insist that I call her "mamá", and my wife calls "mamá" my mother as well (and they are both happy about it), but I am sure this is not the norm. My guess is that the most common way to address a mother in law is just by using her name.