Closing multiple opportunities using workflow

Hi all,

For a requirement of a client I want to be able to close multiple opportunities (bulk closing). I have already figured out and tested this by creating an on-demand workflow. 

However, this way it is not possible to fill in competitor, actual revenue etc., which is possible if you close opportunities one by one.

Can someone guide me how to set up my workflow so I can fill in the required fields?

I appreciate the response!

Thanks,

Emma