Double Genitive

[Humble]

Hi, dear friends,
I am asking you to clarify the usage of the Genitive.
Mrs. Bliar has a son. Her son has a puppy.
1. It is the puppy of Mrs.Bliar’s son.
2. It is Mrs. Bliar’s son’s puppy.
3. It is Mrs. Bliar son’s puppy.

I know I’m safe with #1. Perhaps it’s (a) better style and easier for listeners’ brains. Are the others correct, too? Which is preferable?
TIA

[Tdol]

2 is fine. I think 3 is wrong, though people might say it colloquially to be lazy.

[Humble]

Thanks, Tdol.