PEI Greens and Liberals tied, leaving unclear who serves as the main opposition party

A by-election has left PEI's Greens and Liberals tied at four seats each in the 27-seat legislature. The governing Conservatives hold 18 seats; one belongs to an Independent. The tie raises a question: which party becomes the Official Opposition — the party that leads the pushback against government, and gets extra staff, committee roles and funding to do it.