EP5 to EP6 after migration page changes are not reflected in roles

We are currently investigating an upgrade from EP5 to EP6. We have migrated all our content across. We have many roles which share the same pages. In EP5 any changes to a page would be reflected in all roles to which it was atteched. This does not seem to be the case in EP6.

Has anybody elseexperienced this? Is it because the links are not retained during the migration??

We really don't want to have to rebuild all the roles (we have hundreds of them). Is there another way around this??