umm.. thats not quite what a multimanager does, a multimanager just triggers different things at different times...
With the multi-manager entity selected, and viewing it's properties, click off 'smart edit'...
Now, click 'add'..
Type in the name of the entity you want triggered, and the time in the next blank..
example:
To trigger 'lighta' in .8 seconds after the mm is triggered it would be,
Blank 1: lighta
Blank 2: .8
You can add up to 16 items to be triggered,
This way when you trigger the mm it will trigger all the things in the mm at specific times.
It doesn't deplict explosions or anything. An explosion can be triggered using this however.