If that's the way the Free-DC admins want it, then one of you should register the channel, so it's not 'owned' by Marc, and you will maintain some semblance of control over the channel.
Keep using #lobby on Marc & DP's new network
Keep using Marc & DP's new network, but in our own channel
Switch to new, Free-DC 'owned' servers provided by IB & Dyyryath
Look for other DC chat groups to work with
Some other option Dyyryath wasn't smart enough to think of
If that's the way the Free-DC admins want it, then one of you should register the channel, so it's not 'owned' by Marc, and you will maintain some semblance of control over the channel.