If you're trying to apply for the DTV can you clarify exactly how your business runs online and how you would remotely administer it. There is no family business visa.
They can apply as dependant through any country where their visa status allows an applicant. They will reference your DTV number and and provide their own financials or you'll also supply a sponsorship letter.
The OA might work for you, the only real expense is mandatory health insurance, you can keep your money in Canada and squeeze 2 years out of this Visa without the need to extend in Thailand. At the end of the two years you could go back to Canada and apply for another OA. Rinse and repeat