Halliwell got engaged to Formula One racing boss Christian Horner in November (14) and the nuptials are expected to take place at Syon Park House in London in May (15).
Her four former bandmates are reportedly trying to clear their busy work schedules so the five-piece can reunite for the first time since the opening of the Spice Girls musical in 2012.
A source tells Britain's The Sun newspaper, "Geri is desperate for all the girls to be there. Some of their schedules are tighter than others but Geri's happy it appears there'll be a full-on reunion at her ceremony."
Earlier this week (beg09Feb15), four previously unreleased Spice Girls songs leaked online.