should this workflow be the only chance to get write access to a page? Yes Lets say If I Aquire the doc I will have write access to this page and If I invite someone for collaboration they also should be able to write the content.
* or do all authors, which can be invited to this workflow, already have write access to that page (even if they are not part of this workflow)? No.. Other authors will not have access before collaboration to this page.
And we are thinking to implement component locking ..
I don't think that there is a good way to implement this requirement. Locking does not help, because locking only allows the owner of the lock to modify the page, but no other person.
The only way which will work is to create an group, make these 2 users member of it and give the group the permission to modify the page. When this operation is completed, remove the group. This is cumbersome, and will create a huge amount of dynamically created groups, which come and go.
Instead I would question the business workflow. I don't know the details behind your requirement, but before I would start to implement such an approach, I would try to find another way which can be implemented with less customizations.