Only

[kadambarivaijainthi]

which is right - He is an only son for his parents or He is the only son to his parents or He is an only son to his parents ?

[bhaisahab]

which is right - He is an only son for his parents or He is the only son to his parents or He is an only son to his parents ?

I would say, 'He is his parent's only son.'

[Offroad]

which is right - He is an only son for his parents or He is the only son to his parents or He is an only son to his parents ?

kadambarivaijainthi, how many names are there in this 'name'?

by 'only son' you mean 'only child'? If so, to be honest, it's right, to me.

He's an only child to his parents. ( a bit odd, but still can't see anything wrong)

[Barb_D]

In a family of six girls and one boy, you can be an only son without being the only child.

I find the inclusion of "his parents" redundant. Whose son would be be?

He is the only son.

[Offroad]

Good point, Barb.

Also,

He's an only child.