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It sounds like this situation is very complex. Blended families are difficult but not impossible. For the respect level to change you have to get your girlfriend on board. If she allows disrespect and bad behavior then you can't change it alone. She has to have appropriate boundaries or her children don't have them either. Often the mate tries to gain respect but with the partner being complacent things can get out of hand. I would find a relationship counselor to show her that she is displaying no boundaries and the household is not working. She has to hear that bad behavior should have certain consequences. This can help you get along as a couple and a family. She has to present to them a functional relationship that has certain repercussions when you can't function within normal boundaries. You as a family may not be able to resolve this on your own. Try to move her towards addressing her children or challenge them as a couple. Without mom you will face minimal change.
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