Hi Jack and Kannik,
Please ensure that PHITSANU PHUMPHUANG and SOMSAK PREMSAK have the following things ready.
1. Original Passport
2. 2 passport size photo with white background
3. Original Yellow Certificate
4. Signed Visa application form as attached (I will explain to you below for Somsak visa application)
Kannika,
Since PHITSANU PHUMPHUANG went to Congo, please ask him to fill up this part in page 1. When did he go and where.