Experience Letter - 3 companies Acquisition scenario

Company "111" Started its operations on Jan-01-2015 and employed an employee named as "ABC" and employee joined on Jan-01-2015.
Company "222" acquired Old Company "111" on Jan-01-2016 and took the employee "ABC" into "222"
Company "333" acquired Old Company "222" on Jan-01-2017 and took the employee "ABC" into 333.
Employee "ABC" put his resignation on March-31-2017.
Note:- For all 3 companies, "111", "222" "333", the management, directors are the same.
How company "333" can issue experience letter?

Dear Appleboycat,
Your method of explanation is good. I appreciate bringing utmost clarity to the post.
Company "333" can issue the experience letter on their behalf as well as the for the preceding two company. When a company is taken over, nothing wrong if the current company issues the experience letter for the tenure spent in the acquired company. In your case, the difference is that it has become a sequence since there were two preceding take overs.
Thanks,
Dinesh Divekar