TV celebrity cosmetic surgeon Dr Piyapong Howilailak and his wife Pavena Namsongkhram have been summoned to give information to police on May 11 about their endorsement of a product under the "Magic Skin" brand, a senior police officer said on Sunday
The product has been at the centre of allegations over its dubious legality and alleged sub-standard quality.
The couple became famous on the "Take Me Out" dating game show, where they reportedly first met and fell in love.
National police deputy chief Pol General Weerachai Songmetta said that the suspect in the case, Kasit Worachington, who was arrested previously and released on bail, was summoned to meet police again on May 11.
On that day, Kasit would hear an additional charge of violating advertising laws for offences allegedly committed on occasions other than those already cited in his original charges related to advertising laws and fraud.
Police last week summoned nine Thai celebrities - from a group of 59 who reportedly advertised the firm's products - to testify to them between May 4 and 7.
Several celebrities stepped forward to give testimony in advance on Friday, identifying themselves as "witnesses" and maintaining their innocence.
They included Pitchanart "May" Sakhakorn, Napapa "Patt" Tantrakul, Orapan "Aoffy Maxim" Dansiriwattanakun, and Nonthaporn "Ying Yae" Theerawattanasook.