Merger & Acquisition - does the new company issue appointment letter?

In case of merger and acquisition If Manpower is retained from the older company, does the new company has to issue appointment letter ? is there any provision given by government
I am requesting to all plz solve my query

Only the management has changed. The employees have joined a company and not the management. Hence, no fresh appointment need to be given. But, there could be anxiety and uncertainity during the transition period. To just allay the fears, a circular may be issued stating that the new management has taken over the company and the management is looking forward to the cooperation of employees to make the organisation great. There is no change in employee terms of appointment and the new management is looking forward to make the place of work an enriching experience.
This is what I did when we took over two PSU units in two different parts of the world.

1. You have to issue letters to all employees informing them about the merger and their absorption into new entity on the similar terms & conditions of employment.Also assuring them that they continue to work as usual.
2. Employees have to take the letter giving their acceptance on the letter.

Apart from what Mr. Bharat has mentioned the terms should mention clearly about the statutory obligation of the older company e.g. Gratuity