Hmmmm, seems like a case of a child who grew up without being taught proper manners. And what is DH's defense of his daughter not telling both a sincere 'thank-you'?  So, she tells him in private? WTH? Are 'thank-you's" a secret? Are they something one is suppose to only half declare? 

This is on your Dh as well as on his ungrateful daughter. He is enabling her rude behavior. 

While I suppose he can  not force the adult daughter to express appreciation to you, he can indeed stop rewarding her ill behavior. He cold stop handing out and/or treating the woman to such nice presents, dinner and lovely weekends. Ah, but he's not going to do that, is he? Nope. Or he'd have done it as soon as the ill behavior started. He also would have called SD out on her rudeness to you right there at the dining table or the end of the weekend treat you and Dh hosted. 

So what now? Do you just keep buying, paying for and resenting the lack of appreciation? Or do you inform your Dh that your money and any part of making the gift or outing is done and over? To put it rough, if the dog keeps biting you, why keep petting it? 

My SD was like this and she is even older than yours. Only gave her dad credit for presents that I had picked out or had even hand made.

I put up with that for years, and other treatment, even though my DH told SD over and over again that I was responsible for picking out the presents. Her response was that she did not need to give me credit because everyone knew the woman picked out the presents. She simply wanted to pretend that I did not exist.  When I got tired of it (along with her other inappropriate behavior) I disengaged, and let DH handle her on his own, including all presents for her and the Royal Spawn (gift cards).

After years of being away from the situation, I think our SD's were trying to hold on a piece of their father that is like the good old days, that is theirs only. Their father's recognize this and don't want to cut that off. Unfortunately that results in rudeness to the other person in Dad's life. 

You may be best just removing yourself from the situation entirely so you don't witness it. Tell your DH that you feel like their relationship would be better off without you involved.

My DH used to say this a lot too, "She told me to thank you, she told me to tell you she was sorry."  None of which ever happened. She never thanked me or ever apologized in the first place to him, he was just saying the words to appease me.  I realized I was the the family dog, yeah the hand needed to stay in...no more of me going back for the same ol trash treatment. I think you are feeling this way too now.

Just as Sacrificial states above,  your emotional relief can only come from removing yourself from your DH and his DD's dysfuction, of which you did not cause nor create.  This sickness belongs to them, not you; stay away from it.  I learned if I get around it, it is very contagious and I want no part of it.  Life is too short to be with ungrateful people or people who want to make certain you know--- they could care less about you.

It is not perfect this way, but it is a lot better and you will be soooo much happier!

Should an adult woman thank you for the birthday dinners and gifts that her father has been supplying her whole life and will continue to supply no matter if you are around or not? 

You should not try to take credit for someone else's actions. 

Perhaps you are feeling a little jealousy about their relationship and want the gratitude, as well, as a way for SD to acknowlege your relationship and position with your BF? Fiance? DH?

It is possible to spoil one’s  biological child and still love one’s spouse at the same time. I tend to spoil DD a lot because she only has one mom and I want to be there for my child. DH gets jealous sometimes because he wants me to spoil his own daughter. I won’t however ever stop taking care of my daughter because DH wants me to stop. Yes it’s out of line for an adult child to still want outrageous gifts if it’s coming out of your pooled money but if your money isn’t pooled and he’s not having you cover his living expenses and he still treats you like a wife then I would not make a big deal out of it. I would also have negative feelings if the adult child never reciprocated and only takes takes takes. DH and I go out of our way to make sure both parents get nice gifts for Christmas and birthdays. Maybe DH didn’t teach his daughter about reciprocation. Maybe drop her a note close to DHs birthday that it would mean a lot for her to get her father a gift. I have to text DD and skids about father’s day, Christmas and DHs birthday and ask them what they’d like to get their father for these occasions and they always play along and thank me. I make them make cards for him too. DH does this with his kids for me. So maybe you guys just have to remind her. 

I went through this for a good part fo 20 years with SD, who was raised as an entitled, spoiled only child.  I appreciate DH's love for her but I didn't appreciate the way she treated me - and THAT is what I think gets to you.

Like you, I went out of my way to choose special gifts for SD.  I helped to pay for her and her husband to go with us on vacations - lodging and food.  They were so tight they never did pay for a meal - or even the tip.  When they visited us in a home I paid for they took it over as if they owned it, not asking if they could use something, just taking over.  Meanwhile, being extremely hostile and rude to me, treating me as if I was invisible and stupid. 

As far as gifts, SD expected them but never returned the sentiments.  When I DID actually get a gift for Christmas from her it was a bottle of out-dated maple syrup she had pulled out of her cupboard at the last minute and a minute jar of jam.  Like you, I never received a thank you for anything but I can't really remember her thanking DH either.  She never has sent DH Birthday presents or Father's Day cards.  Quite frankly, I appears she can not go beyond herself enough to think of anyone else.

I finally suggested to DH that he pay for his family and I pay for mine.  Odd that when the money was coming out of his pocket he quit being so generous.  LOL  I disengaged and let DH take care of all communication, etc.  After all, he's the one who helped to 'shape' her into the ungrateful, self-centered a$$ she is today.  On Father's day he gets a card from the animals or his Birthday I try to do something special for him.  If SD fails to honor him it's between SD and DH.

At first disengaging is hard but but after a while it dawns on you how truly liberating it is.  Every human being deserves to live with mutual respect.  If you think the give and take between SD and yourself is a bit unbalanced take yourself out of the equation.

After 8 years of similar behavior I finally dropped the rope with my husband's ingrate of a daughter. Her birthday no longer exists for me, and DH manages to send her a text. DH's birthday is 5 days after mine, then his daughter's is two weeks later. One year she had the nerve to complain that the gift that I ordered online should have been shipped to me first so that I could wrap it and then ship it to her in another state, instead of having it shipped directly to her.  Oh, and she complained that I didn't also send a card.  For my birthday a few weeks previous she put happy birthday on Facebook.   

This is very familiar -- my SD only goes to the most expensive restaurants with her father. And I'm never invited. But I don't eat snails with raspberry sauce, so I don't care.

I did manage to put a stop to SD's other outrageous requests for money -- plane tickets, cars, etc. Try making an argument to your husband that you are on the decline for earning potential and it's time for you to get into savings mode so you won't be dependent on his kids for anything when you've retired. Make it all about his kids. That's all they understand.

One or two expensive dinners a year won't kill your budget. It's those $2500 plane tickets that do the big financial damage. Chip away at that "tradition" and forget about the dinners. You can't get ahead of a dinner here or there, but if you can get ahead of the really big-ticket items, you'll be in better shape.