Hello Raynet,
If you are seeking to "lock" some consultants, I would suggest to look for authorizations there are some possibilities going through class type / you can define authorization groups and so on...and maybe why not a specific object with a little exit/modification at the transaction start (to get the transaction code - look in the menu area related to the MM customizing).
Otherwise, as mentioned name a "super coordinator" who receive the change requests on paper and execute them (this can be combine with the authorizations).
Alex