my humble opion it is all about give give and take.
if u are comfortable with your children surname being your wife surname so be it dont let anyone influnce u at the end of the day its your own family.
if u dont feel comfortable and againts it u better tell her it is impossible to follow the way she wanted it if she really want her way then it is up to u either u give in or u can tell her to find a husband who willing to give the child her surname. this there a risk u guys will break up.
me a malay and my dear wife a chinese and when my daugther born her surname is my dad name do i care what other think? no i dont its my life and my family lucky for meboth parent and inlaw very supportive