Surname change of new born without changing Parents' existing surname

Dear Sir, I need urgent help in this case: My full name is Abhishek Raval, My wife's is Priyanka Patel (she has continued her paternal name after marriage in all her professional documents, though we have marriage certificate in place). Now I want to change my new born Son's surname from "RAVAL" (as per mine as a father) to "Rajyaguru"(new born's son's independant surname. Below facts to be considered: 1.Maternity Hospital has nothing to do with my surname so they can write my name as I suggest them to write as father like Abhishek Raval or Abhishek Rajyaguru., 2. I also inquired in nearby Municipal Civik center and they told we will not ask for any documents of parents in the name of Abhishek Rajyaguru while issuing the birth certificate, and municipality will follow what maternity hospital sends information online. 3.Birth certificate only depicts child's FIRSTNAME only not his own SURNAME...only mentioned FULLNAME of Parents individually. Now My question: 1.Is it possible to change my Son's surname independently without changing my surname if suggest to write my surname as 'Rajyaguru' at maternity hospital? 2. if yes, any further complications by myself or my son has to face while school admission,Adhar card visa, passport applications etc because father & son is having separate surnames? 3. If point #1 is not possible, what is the best way to change my son's surname?