Someone (mag-) celebrates on the eve of a celebration or fiesta.
Magdispiras kami anchan pistan minatay.
We will celebrate on the eve when it is the fiesta of the dead.
Someone (machi-) participates on the eve of a fiesta or holiday with others.
Mangay ta machidispiras do Idi.
We participate on the eve of the fiesta at Idi.