The meeting of whips representing the coalition and opposition parties, and the senate agreed to allow 57 Democrat MPs to debate the amendments on the future of senators in the second reading.
The issue was the source of the brawl in the joint sitting on Tuesday, as Parliament Speaker Somsak Kiatsuranont wanted to limit the debate by the opposition party to two members. All 57 Democrat MPs had reserved the right to debate on the make-up of the upper house in the session after it passed the first reading and was scrutinised by a committee.
Mr Somsak's position led to protests on the floor and the situation escalated when he called in parliamentary police to safeguard him. The chaos later forced the debate to adjourn.
The meeting on Wednesday did not bring up the ugly brawl as the whips did not want to revive the conflict, Deputy House Speaker Charoen Chankomol, who attended the talks, said. They agreed to allow the 57 Democrat MPs signed up for the debate to speak.
Despite a better atmosphere, the debate was delayed for three hours as some opposition MPs and senators were locked in a protest with the Pheu Thai Party on the voting of Section 1 of the bill proposed by lawmakers led by Samart Kaewmeechai. The section, which passed on Tuesday, involves the title of the bill.
The thrust of the bill is to end the selection of senators and call for all senators to be elected by eligible voters.
Opposition chief whip Jurin Laksanavisit said on Wednesday that the Democrats would block the proposed composition of the senate as it was "political collusion" between the government and some senators. It could lead to a "parade" of relatives of politicians through the upper house via senate elections, he added.
Pheu Thai viewed the selected senators as a by-product of the constitution written by people handpicked by the coup makers who ousted Thaksin Shinawatra as prime minister in 2006.
The selected senators are considered by the charter writers to balance the upper house with those elected by voters.
The joint meeting voted 349-157 on Section 2, which says the bill will be enforced one day after it is officially announced in the Royal Gazette.