curious, how did Nelson/Marlborough clubs like Richmond Athletic previously win the right to play in the MPL? was there a promotion playoff structure in place like with the Central League, or was an application and $$$ needed?
Yes there was a playoff series between the winner's of the various leagues, if more than one team were seeking promotion.
Some seasons those teams played off against the last placed MPL side, before the bottom placed MPL side faced automatic relegation.
Richmond won promotion for the 'new' eight team 2007 season. In 2006 there were ten teams in the MPL so 9th and 10th placed teams - Christchurch United and New Brighton, were automatically dropped with the 8th placed team Avon United then facing the play-offs.
Both Burnside and Richmond were seeking promotion with Richmond winning the two leg play-offs, 4 - 2 on aggregate with Richmond then defeating Avon 3 - 2 in aggregate.
Richmond finished in 7th place in 2007 and were 8th in 2008 and were relegated after loosing out to ChCh United in the play-off series 6 - 0 on aggregate.