How to restrict the user to change the project structure but not the documents?

Hi,

I have created one project assigning different users in Solution manger. I want to risitrict some of the users to change the project structure but simultaneously allwoing the project documents to be created, edited or deleted using solar01 under Project documentation tab. For that I have followed the steps provided in the follwoing link.

http://wiki.scn.sap.com/wiki/display/SM/Howto+Restrict+Changes+to+Project+Nodes+to+Assigned+Team+Members

I am able to restrict the users to change the project structure, but I am not able to allow access to the project documents. It gives me the message "You are not authorised to change the project". This fulfills my one of the requirements. But, Is there any way  to restrict the user to change the project structure but not the documents?. Any help will be apperitiated.

Thanks,

Rutvik Uapdhyay.