How to issue experience letter of a Proprietorship Company converted to Pvt Ltd with different name?

Hello, My company was proprietorship firm until 6 month ago. We have now become a privately held company .Company name is different now but management is the same.
I have some employee working with me prior to this change.Now one of them want to resign & I have to issue experience letter.
How should I issue experience letter.please give me detailed format.
I also want to know if I need to give a new set of offer letter to all the employees after conversion date or a letter stating the conversion will suffice .How to handle this situation.
Please advise.
Regards,
Piush.

The company's articles of association or its Memorandum of Association is it providing for continuity of service of these employees. Unless it is so, there cannot be any continuing liability as the nature of the firm has undergone change. Is the Pvt Ltd Company undertaking the assets and liabilities of proprietary firm. All these issues need to be looked into. If you have not given offer of appointment already, it is high time you should issue whereby you can make it specific with regard to the previous service