How can a workbook grant access to another one
 

Hi everyone,
I'm looking to solve how a workook can grant access to another one.
Here more details:

I have a template, let call it "BuildID.xlt", which will allow users
to know how a specific ID shall be built based on some criterias. In
some specific cases, an ID can't be built based with the provided
criterias and for this, I would like to built a credential internal
ID, like INT1, INT2, INT3 and so on.
The internal ID has to be unique.

For this, I have created a central protected workbook, let's call it
"CentralID.xls" where the last ID used will be stored.
This workbook has 3 user profiles: 1. "Automated Access", 2.
"Specialist", 3. "Other".
Profile "Other" will open the workbook in read only mode (the profile
will be provided in a userform).
Profile "Specialist" will open the wb in read-write mode, in order to
allow to do manual corrections (again, profile provided from a
userform).
Profile "Automated Access" is reserved when the "BuildID.xlt" accesses
the "CentralID.xls".

How can I pass the profile from the "BuildID.xlt" to "CentralID.xls" ?

At the same time, if 2 users try to access the "CentralID.xls" at the
same time, User1 will block the workbook. The module triggered by
User2 will try every 2 seconds to access the same workbook. As soon as
User1 has finished, User2 will be allowed to access the workbook.
Futhermore, if the "CentralID.xls" is used by the profile
"Specialist", other users will get a corresponding message that
"CentralID.xls" is not available at the moment.

How is it possible to manage the information flow between the 2
workbooks ?

Thanks a lot for any help !
Joel