Can I sponsor my girlfriend for a DTV visa in Thailand if we're not married?

I'm planning to apply for a DTV (soft power) in a few months and also my partner from the Philippines will also apply.

I'm wondering if she needs the equivalent of 500,000 THB in her account or whether I can write her a sponsorship letter. We are not married. I've got more than 1,000,000 THB in my bank so I can cover both our applications. We've known each other for 2 years and have loads of evidence that our relationship is genuine.

I don't really want to transfer the money to her account for three reasons. 1) The cost of the transfer 2) Lower interest rates 3) Our lack of trust in Philippines banks.

We are planning to make both applications in the Philippines.

Has anyone had any experience of applying with a sponsorship letter when the person being sponsored is not married (or not a direct family member) of the person sponsoring?

Thanks in advance