Transferred Employees Formalities

Dear All,
I am working in a retail sector, (under Bombay shop & establishment act, Maharashtra). Few of our employees were transferred to another branch in the same city, in mid of the month. My queries are:
1) From where do the salary of the that month should be processed ? (we process payroll branch wise & not centralized)
2) Should we issue transfer letter, to be safe in case?
Thanks in advance
27th July 2014 From India, Pune

1) From where do the salary of the that month should be processed ? (we process payroll branch wise & not centralized) - If payroll is processed branch wise then why process the salary from date of joining in new branch
2) Should we issue transfer letter, to be safe in case? - If transfer is for longer duration then its better to issue transfer letter else deputation letter will serve the purpose.
27th July 2014 From India, Pune