hello
how to add Call Sub Workflow item to a multi-steps activity containing a task event
I did add it before in a previous process, now when I try to add it to multi step the designer wont allow me to.
it has to be added to the task activity in order to be executed for each user in a group
The old process where I was able to add it
the new process where I'm not able to 
Hmmm... I don't recall a version where this was possible. What I have been doing in situations where this is necessary is create a SmartObject that kicks off the necessary sub processes via API and invoke that as needed from the workflow.
If you have access to the SmartObject that returns you the list of people in that group then you could use a for-each activity to do the same.
Cheers
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