How to apply for the primary applicant position if previous owner died

last year Under Construction property was purchased, where my father was Primary Applicant and Me (Only Son) and my wife were Co applicant. No bank loan taken for the partial payment and next payment is due to Builder after 1 year. Now due to sudden death of my father due to cardiac arrest i want to be Primary applicant. Does i need to take NOC from my mother and from my 2 younger married sisters. If noc is not required than how can i proceed.