In reality, a merger between two parties that are of such mis-matched size - would essentially be a takeover. The NDP has 37 MPs, the Greens Zero. The NDP has over 100,000 members and MPPs and organization across Canada. The Greens have a couple of thousand members in the whole country and no organization to speak of. You can call it a "merger", but in practice the NDP would quickly become about 95% of the new party and we would be right back to where we were before the Green party came into existence.