Joining public match rather than starting private.

[Skeetss]

A lot of the Adventure profiles start a new private game in order to refresh the bounties available. Looking through the files, most have the line:

<GameParams act="OpenWorld" resumeFromSave="False" isPrivate="True" numGames="-1" />

I want the bot to instead join a public match, so I tried to change the line to:

<GameParams act="OpenWorld" resumeFromSave="False" isPrivate="False" numGames="-1" />

but it creates a public game rather than joining one. How can I force it to join one rather than create one?