Hello Shubham,
if a BOPF BO is transported to a customer and it is not extensible, the customer is not allowed to add further actions/determinations/validations/nodes to that BO using the BOPF Configuration UI transaction. If this is required, the corresponding BOPF BO must be maintained as extensible. In that case, the customer is allowed to create an extension BO in order to implement own actions/determinations/validations/nodes. A short introduction in the extensibility of BOPF BOs you find here: http://scn.sap.com/community/abap/blog/2013/02/22/navigating-the-bopf-part-5--enhancement-techniques
Best regards
Tilmann
