@Alf **********
this is from Vancouver Thai Consulate..
For the purpose of visiting family in Thailand or visiting as a spouse of a Thai national:
The applicant must present a valid and effective marriage certificate and a copy of the spouse’s Thai Passport or Thai National I.D. card. Fiancés are not included in this category.
To visit as the relative of a Thai national, the applicant must show documents proving such a relationship.
For multiple entry: required document to proof monthly income minimum 40,000 Baht (for last two month) or Bank balance 400,000 Baht