Transitioning from Proprietary to Public: Do We Need New Offer Letters for Employees?

I work in an IT company as an HR. The company was a proprietary firm, and since 2017, it has been converted to a public limited company. We issued offer letters to all employees for the proprietary company. Now that the company is public limited, I need to know if I have to issue new offer letters on the public limited company letterhead. If so, what joining date and salary should I write in the offer letter for a 5-year experienced employee?

The entity that issued the letter does not legally exist. Therefore, you must issue a two-lined letter to all employees: line one, informing them of the company name change from X to Y; line two, informing them that the terms and conditions of the earlier letter dated --- will remain unchanged.

It is essential that the letter be printed on the new company letterhead, and employees should acknowledge receipt of the same.