Oi all ,
Here is a 100% working method.
Join a game in a group with 1 of your friend.Both changes backup's call parameters with
+ gameplay + backups ..... Friends / Clans
Join a safe house ,
now Player 1 quit the group via
and the Social Tab
PLayer 2 stand in front of a Matchmaking computer in this safe house while player 1 go outside to kill himself with a grenade , as soon as Player 1 send a Backup request , player 2 search with
in the matchmaking's computer the backup TAB , press
a second tab to search players .... in few seconds you will spawn near Player 1 to revive him. Achievement will pop.
Sorry for my French / english translation , hope this video will help.