Thanks for your question. My name is ***** ***** I'd like to help you out.
From what you've described, it does sound like your boyfriend goes out of his way to provide for his oldest daughter and that she can monopolize his attention even when you're around. This may come from good intentions on his part, and he may only want her to be happy and honestly feel like he is doing the best he can for her. However it sounds like his priorities are focused mainly on her, and that there is a large difference in the way that he treats her as compared to the way he treats his younger daughter and yourself. After a while it is only natural to feel frustrated with that type of situation.
Considering that his daughters are now grown adults, then as his partner it seems only fair and reasonable that you should expect to be one of the top priorities in his life and treated that way. If you're not being treated that way, then it seems less about you being greedy, and more about wanting to be treated as a higher priority in his life. After having been together for 11 years that seems understandable, and would be different if you had recently started dating or had only been together for a short time.
To some extent if he is in denial about his over-involvement in his eldest daughter's life, there may only be limited progress you can make until he is willing to admit this. However I think it is safe to say that your concerns are justified, and that wanting to be treated like a higher priority seems only natural and appropriate considering your relationship together, and not the result of greed. I definitely wish you the best with all of this, and if there's anything else I can do to help just let me know.