Question regarding name Change in US and Child's last name

[Lion Star 2]

Dear All,

I want to ask a question, I recently moved to US and got 10 years IR-1 Green Card. My wife is US Citizen, she wants to change her last name with my name. 

My first name on green card and passport is 

Muhammad Amir

My last name/surname on green card and passport is

Chaudhry

My wife's first name is Nida

My wife's last name/surname is Khan

Now question is that what will be my wife's last name as she wants to fill forms for name change and we don't want to do any mistake:

He last name will be Amir Chaudhry or just Chaudhry?

Also my wife is pregnant and hospital has sent us forms regarding name of new born child. What should we write in last name of our child Amir Chaudhry or Just Chaudhry? As we don't want to change name of new born child in future. 

My wife wants same last name of new born child and her name.

Kindly reply its really confusing. 

 

[little immigrant 801]

Is Amir your First, middle or last name? 

[Lion Star 2]

My first name is Muhammad Amir no middle name and last name is Chaudhry.

 

[little immigrant 801]

Then your wife and baby will be Chaudhry. 

[Lion Star 2]

Thanks a lot.