When the rehatnamas state to read Jap and Jaap they actually refer to reading banis from two sources Aad Sri Guru Granth Sahib and Sri Dasam Granth. The reference is made to first bani of each source. This doesn’t mean that only two banis should be read. During Amrit there are five pyaras and each one is required to recite a bani. Hence, five banis are required. If only two banis are to be read then what is the role of other three pyaras in preparation of Amrit? Only hypocrite missionaries would make up excuses to deny this fact.
Bijla Singh's post in Nitnem Rehatmarayada Vs Rehatnama was marked as the answer