Yes, it is possible to have multiple DJs. When you sign up for your Live365 broadcaster account, your station is issued credentials for going live (we call it 'Live DJ'). You can give other trusted DJs these credential such that they can take over the stream remotely using programs like Mixxx, BUTT, PlayIt Live etc.
Please note: Once your remote DJ is finished with their session they must turn off the encoder (disconnect Mixxx, BUTT, etc) to allow any subsequent DJ to launch their show. This means that the previous session must disconnect by the DJ prior to any another DJs launching their shows. Turning off the encoder will also allow the regularly scheduled Live365 programming to resume.
Be careful to whom you give your Live DJ credentials. Find instructions on how to find your LiveDJ credentials here.