When we play our Online Club games, and we have a half table, the Tournament Director brings in substitutes to make up Full tables.

The substitutes are paid for by the Host Club, so they play for FREE.  A cheap way of playing in many tournaments - you just need to be willing to play with anyone - whoever the TD pairs you with.  (However, the TD will normally try and get people from the same country, and at the same level)

You can register to be available to play - and wait to be invited.  You can decline the invite, but if you decline too many, the TD will become aware - and ignore you on the list.

To Register - click on Competitive, All Tournaments.  At the bottom of the list there is a blue box entitled Substitutes.  Click this box and register.  Cant guarantee a game, but you never know, and if you're chosen for an EBU event - could gain masterpoints!  

Alternatively. obtain the vEBU number (from the pending games) and send a BBO message, saying you are willing to be a Sub in their game.  Be online at the start time with a chance of being invited.