Re: How to be a BUDDY of your mother in law?
the best advice i got about this is to treat your MIL like you treat your boss. give her respect, be open and honest with her, communicate, and keep your distance. familiarity breeds contempt, IMO, and never is this more apparent than between women and their daughter's in law.
also, in my experience, the relationship your husband will have with your parents will always be more chilled and relaxed than what you will have with your mil. its unfortunate, but a fact of life. comparing the two won't help- so don't.
try to build your relationship with your mil independent of any expectations- its hard, but it can be done, i think. she will always be his mother, and she will always have an opinion. accept this and learn to deal with it. you can express yourself without being rude or insensitive, but at the same time its really important to know your limits and boundaries and make her aware of them too.