Rollovers/transfers from one 529 beneficiary to another

I am owner of several 529 education plan accounts for 8 grandchildren and great grandchildren. I have one grandchild who will not use all the assets in his account and I want to rollover or transfer some of those assets to another grandchild or great grandchild. Are there any restrictions in doing this as the owner of all the accounts?
How do i go about making such rollovers/transfers? Thanks, Harry

Terry Says:  This is technical, but important — and I wanted to get it exactly right.  So I turned to Joe Hurley, whose website www.SavingforCollege.com is always my first source.  On his blog there, Joe can answer ALL these questions about 529 plans.  Here is what Joe wrote to me when I posed your question:

The beneficiary on a 529 account can be changed to another member of the beneficiary’s family. Since “family” by definition includes first cousins, the grandparent can easily change the beneficiary on the account to another grandchild by simply submitting the 529 plan’s beneficiary change form. This is not called a rollover, it is just a beneficiary change.

If the grandparent wishes to spread the excess 529 funds to several of the other grandchildren, this can be done through rollovers. Simply have portions of the account transferred (rolled over) to the accounts already established for the other grandchildren.