do all these same people who believe in the respect that should go with calling your husband 'aap' make their younger brothers, sisters and cousins call them bhai, baji and apa?
absolutely.
that's how we were brought up.
in fact, in my immediate family it was impolite to even say the name.
my eldest brother is "bhaijan" the next is "bhaisaheb" and so on.....even the kids say "Uncle bhaijan" and "Uncle bhaisaheb".....LOL...... (we only started with the mamu and chachu thing in this generation)
I am just "baji".
my in-laws were raised differently so it is still awkward for me when I hear my husband call his eldest brother just by the name. when I joined the family I refused to do that and added "bhaijan" to it. I think I earned some respect there just by doing that.
for those that find using "aap" formal......try watching some older Indian flicks (black and white) and see how romantic those couples appear......