ANSWER
According to the Notification of the MOPH (No. 208) B.E. 2543 (2000) Re: Cream, there are no specific regulations that stipulate the usage of vitamin and mineral in sweetened creamer. Submission for approval would be required according to FDA and the process may take around 1-2 months. The conditions to make claim in sweetened creamer are unclear at the moment.
References
Ministry of Public Health Thailand. (2000). Notification of the MOPH (No. 208) B.E. 2543 (2000) Re: Cream.