Maintainability of 151 application for amendment to a consent decree

Question 1. Can a decree be modified / amended u/s 151 due to change in circumstances ie maintainability of the Application 2. What are the remedies available to the Husband to counter the case My Estranged spouse/Wife has filed Miscellaneous Application seeking modification / Amendment of a Decree under section 151. What is she wants to Amendment/Modification # She wants permanent custody of the child but as per decree it is joint custody under change of circumstances as she wants to relocate to U.K Background of the case #Divorce files by wife in 2010 # Mutual Consent Decree obtained in 2014 # Mutual Consent terms part of the decree other terms relating to child A- Child in joint legal custody B - Physical custody with mother C - Access terms az agreed D- Agreed that child will not be relocated out of INDIA till she attains the age of 18 years E- In case the child is traveling out of India she will travel only on visitors visa for pleasure trip F- Passport of the child with my ex wife Question 1. Can a decree be modified/amended u/s 151 due to change in circumstances ie maintainability of the Application 2. What are the remedies available to the Husband to counter the case