Unfortunately I do not think this is possible, but a solution could just be to use two parallel paths that then meet up and the workflow only continues when both paths are complete.

I have an idea but I have not tried it.

Lets say you have a workflow that has two paths and two activities. Activity A gets assigned and gets partially completed and they click a button called Next. This button click updates a value somewhere in a record to say it is OK to assign task B. The problem is how to know when it is time to assign task B.

You could put a workflow step between start and task B that checks this record for the vlaue that says it is OK to assign task B. You can loop it back to itself but make sure you put a time delay (start rule) on the task so this will only happen every couple of minutes or you could end up with  nasty loop.

You would probably want another activty below these two task activities that have preceedding rules that both have to be completed (I would just use a data field to store a completed value on each step)

Does this help or sound like it meets your question?

The other option could be to have a different workflow for task B that starts when you click the next button. I am sure there are other methods where there is a will there is a way but I usually try the simplest approach.

Thanks for the inputs.

I think its valid if I have the privilage of using two Activites for the same event. but as per the requirement, only one workitem should be created and it should get expired only once  I click the button in last smartform of the wizard.  

So like you mentioned , I used another workflow whch is triggered from the Screen on button Click. 

Still I believe K2 should introduce - multiple Actions from the Workitem for the same instance with options

•This action will expire the Workitem.

•This action wont expire the workitem but you can action it.