It’s a catch 22 situation for applications such as this, because you would technically be in breach of your current visa. You can’t work remotely on an ED visa, so starting and running a business while here and not doing anything else won’t be an issue, but moving forward it possibly might and while only a very small chance, the way Thailand works you just never know what they will do.
Have a partnership for business, and both apply as the same. But 500k each. Any other way you will have issues I think. Don’t do “soft” for your partner if not legally married as you will struggle in the future.
If you use multiple accounts they still have to be in YOUR name only and submitted as a single document, so create a PDF with a cover letter to give explanation as to why more to an one account.
Make sure you apply at the embassy for your area or it will be rejected. And you can’t actually apply in Thailand so would have to leave to a neighbouring country to apply anyways
I use to pay electric as well as many shops. Have also used to pay rent as well to my landlord. But we do direct transfer from my other half’s bank account normally.