岳父、岳母、公公、婆婆

[xianhua]

But my own son-in-law and daughter-in-law call me Dave

Clearly fans of 'Only Fools and Horses'. ;)

[crazy-meiguoren]

But my own son-in-law and daughter-in-law call me Dave

When you knock on their door, and tell them it's Dave, do they answer with "Dave's not here"?

[carlo]

Oh, sorry I misunderstood. My Italian father called his mother-in-law (my grandmother) "signora", "madam", very formal, for forty years. Using her first name would have been unthinkable, but so would have been calling her "mother". Now my (Chinese) wife calls him by his first name, and he doesn't mind, though I think he'd prefer the old-fashioned way -- but that's just a bit beyond our language skills at the moment. Although I have met other families (in the south of Italy, mainly) where in-laws are called Mom and Dad. So it depends really. For me it took some getting used to.

[Lu]

My parents (in the Netherlands) call each others' parents mom and dad (mam/mama and pap), but address them with the formal you (u), while they address their own parents with the informal you (jij). My sister-not-quite-in-law-but-as-good-as calls my parents by their first names, and with the informal you. So it has changed over time. It also depends on the family I guess, especially if you get along with the in-laws, you'd use first names and the informal you. Personally I think I would feel weird calling someone other than my parents 'mom' and 'dad'.