Wedding Thank you cards to my dad's bosses

[Shannaratiger]

I'm currently writing my wedding thank you cards. My dad's bosses both sent me presents, I have never even met them! One of them sent a card and signed it with his and his wife's name. The other one just gave my dad the present but Dada told me his name.
How should a address the card: to X and Y / Mr and Mrs Name X and name Y or mr and mrs surname...?
Also how do I end it sincerely/ faithfully?
Don't want to get it wrong and upset my dad's bosses ( who are both very rich arabs btw)

I would go with "Dear Mr and Mrs Lastname" (and close "Yours sincerely" -- "Yours faithfully" is for a "Dear Sir" opening).

On the envelope your issue is more taxing -- formal etiquette used to be that it should be addressed to "Mr and Mrs Hisfirstinitial Lastname" but increasingly women object to the Hisfirstinitial. If you're sending it via a work address, though, there's every chance that a PA will actually open the envelope and he'll never see it, so probably not worth fretting about it too much. I'd probably just go with "Mr and Mrs Lastname" on that as well.

Thank you BuckskinnedAstronaut, love the name btw, i was thinking that but as it's a thank you note it's a little bit harder.
It was a lovely bottle of Burberry and a wrap/ scarf and the other a bottle of coco chanel mademoiselle both of which I now love I am very grateful.
Dh isn't as they are very expensive! :)