We have a requirement to lock cost plans after plan updation by project manager and it should be unlocked/able to edit only one group(Authorized group).
Step1. Cost Plan should be Locked, once the project manager updates basic cost values in the time scale value(amount by period).
Step2. Cost plan should be editable for one group after project manager part has been done in the cost plan.
Note : Once Step 1 has been performed even project manager should not update cost plan value. ONLY AUTHORIZED Group should have an edit access for time scale value(amount by period) of cost plan.