All five Spice Girls are to reform for a TV special next year.
Mel C - who, along with Victoria Beckham, previously shunned attempts by Geri Horner, Mel B and Emma Bunton to get the group back together - is said to have been instrumental in getting all her bandmates to reunite for a one-off documentary and a new compilation album following months of negotiations.
A source told The Sun on Sunday newspaper: "The five of them have been locked in secret talks since the summer, and finally they are all on-board for a 2018 reunion.
"As it stands, they will be working together on a series of projects, which will include an album and a TV special celebrating the Spice Girls.
"And getting Victoria to agree has been a coup for everyone involved, given she has always been the person holding back on a reunion.
"The fact she is on board now is down to how much closer the five of them have become recently."
The 'Wannabe' hitmakers have grown closer this year in the wake of Mel B's bitter split from husband Stephen Belafonte - which saw her accuse him of being abusive and getting their nanny pregnant - in March, with Geri's baby son Monty, now 11 months, also said to have been a "uniting force".
The source added: "Things between them were quite icy at the start of the year.
"But gradually the ice thawed, and Mel was the one who drove that. Mel's divorce battle also helped to bring them back together, as did the birth of Geri's son.
"Plans at the moment are still in the early stages, and everything involving the girls tends to be complicated because they are so busy.
!It is not easy to get them all in the same place at the same time.
"But the team behind the reunion are delighted to have made it to this point."
The group are working with their former manager Simon Fuller on the reunion plans.
Geri, 45, recently teased that "bits and bobs" with the rest of the group were still being planned, after she gave up attempted for a reunion to mark their 20th anniversary.
She said: "I really pushed to get everyone back together. It got to the point where I just had to let it go.
"I still love the girls and there are other bits and bobs in the pipeline."