DP adult child problem

[Biscuitfiend1]

Advice needed please.
my DPs adult daughter is, I think, struggling with her dad, our relationship and the blending of our families, I have children too.
she doesn’t live with us but is always asked if she wants to join us when we go out for days and holidays. She often comes but never pays for anything (she works) and often makes snarky comments aimed at her dad and us.
I’m starting to feel really stressed about this as I feel I am trying really hard to get on with her and build a good relationship with her and us. Her dad is soft and won’t confront any disrespect. I get it’s hard for her but would like to think that she could at least try to be civil, or say what she had to say so we can talk it through/help her. am I asking too much?

Surely if one adult is being disrespectful to another you say something yourself? Your dc need to see you stick up for yourself op! Not sure why you paid his dc through uni though.
Does your forehead read MUG? If you are letting her call all the shots in your life then you are a mug imo.

Treating adult children and stepchildren can be a pleasure, particularly when you are delighted to see them and enjoy spending time with them.
I can understand your might feel taken advantage of, if your step daughter does not appear to be enjoying the interaction and is rude to you and her DF.
Time to take a step back, explain the current arrangement is not working and suggest your DH takes SD out alone for the time being and just invite her to the occasional family meal.

There’s clearly significant unresolved issues between her and her dad. How much time do they spend together alone? Without you and your children. That’s priority one.

I think some self reflection as to why you’re so concerned about costs. Presumably he lives with you and your kids and is footing their bill so why not his own kid who he presumably abandoned.

Why are her parents no longer together- death or divorce?

Did you move into her father's house with your kids in tow?

I suspect your SD would prefer to spend one on one time with her dad, without you/your kids. Her dad could do better there.

Why do people attempt to blend families with older kids and adult DC. People being forced together with different personalities , It doesn't work. Your DH should be spending time with her separately to your blended family thing.