Addressing family members

I'll be staying at my friends house for a few days and I was wondering how I should address her parents. [Family name] san? but then how do I solve the problem of directing it specifically at either her father, mother or brother?

Thanks

IMExp, I've used as default (if no first name or nickname is provided), Oku-sama to address the wife and (Last name)~sama for the husband. Start off the most formal and work your way down -- they'll let you know (ask your friend how traditional they are).

I've always been hazy on this too and always screw up when theyre all in the same room.
It might depend on the family. (Last name)~san is standard and used for both husband/wife.Maybe they might give their first names to make it easier for you, in which case (first name)~san is appropriate unless they cast off all formality.

First of all, the Japanese rarely address others by names. You can pretty much get away with having a great conversation while not addressing them at all.

Secondly, if you do address them, the way you do it greatly depends on how old you are.

For example, if you are an adult who is working, calling the husband as "(last name)-san" and his wife as "oku-sama" is okay. But if you are still a student, that may sound too snooty. "Ojisan/obasan" would be better.

"(Friend's name) no otousan/okaasan" would be most safe and common for everybody, though. At least that's how all my son's friends call us.

Of course, if you are speaking in English, "Mr./Ms. (last name)" would be best.