The Nepali Congess statute was not contested by anyone before the present party division. There is no point expressing differences after the party has split. It you look at the party constitution, you will see that Prime Minister Sher Bahadur Deuba was not even a member of the party on 16-19 June (when he held the 'general convention'), because he had already been expelled by the party, on 26 May. He had not challenged the legality of the expulsion or that of the disciplinary committee or the central committee of the party. In fact, on 9 June he had sought a review of the decision of the disciplinary committee by writing to Girija Prasad Koirala, acknowledging him as president of the party.
But even before the time for a review to begin had elapsed (35 days after the application is submitted), on 16-17 June, Deuba called a meeting of party workers for "party unity", and declared it a general convention, also announcing his unanimous election as new president of the party. President of the party of which he was not even a general member! Now the Election Commission is expected to accept the meeting as a general convention and Sher Bahadur Deuba, and not Girija Prasad Koirala, as president of the NC! Otherwise we are told there will be chaos! The sky will fall!
Now note another date: 22 May. That evening, Prime Minister Deuba submitted his recommendation for the dissolution of parliament, and declared fresh elections to His Majesty. The king approved the recommendation the same evening. Such a decision by the king becomes effective immediately, unless specified otherwise. In other words the House of Representatives ceased to exist, and the status of MPs and parliamentary parties became invalid. All MPs, except the Speaker of the House, became former MPs. By his own decision, the prime minister also ended his membership in parliament. The day he was expelled by the party, Deuba was also not the "leader of the parliamentary party", because the party had taken action against a cadre who had vowed to abide by the party constitution and processes, not against the leader of the parliamentary party. Now Deuba claims to have convened the meeting by virtue of being the leader of the parliamentary party, and that was the basis for the decisions that followed.