Accounting treatment of amalgamation of firms.

Dear Members,

When we are doing accounting for Amalgamation of Partnership firms in case where the old books are continued by new firm (i,e,, new books not opened), why do we open Business Puchase account and in whose books it is opened if it is opned in new firm's book why do we transfer even assets and liabilities not taken over and also capital accounts. 

For reference purpose I am attaching may'2014 RTP also in this