Add USD Reference under a specific prim.

[sericicole]

Hello,
I'm begining with ufe ^_^ Maybe i will start with 3 questions
what's the difference between mayaUsd.ufe and ufe ?
How to add an usd reference under a specific prim in python (like right clic menu) ?
How to add a specific prim under another one in python (like right clic menu) ?
Very thx.