Hi ,
Here is a delegation management process :
If you go on holidays , just delegate all your tasks to a specific user.
What it does is checking periodically ( you can chose the frequency ) if there are tasks assigned to you and , if there are , it adds your delegate to the candidates .
I have already included a notification e-mail that lists the tasks assigned , you just need to setup it 
Repository URL : http://community.bonitasoft.com/project/delegation-management