Her maternal aunt and her husband brought her up; do they have the same rights as parents to good treatment?
Question

                In Islam, our parents, especially our mothers are to be honored above all others. There is much about the importance of obeying them and treating them well in both the Quran and the Sunnah.

My mother died after she gave birth to me and I was raised by my mothers aunt and her husband. They were childless and when I came along, with my father's permission, they raised me as their own daughter with much love and indulgence.

I call them mother and father, but I know they are not my real parents, and I am named after my own father and all my life they have encouraged me to maintain a good relationship with my father.

Both my real father and the one who raised me has passed away now. Only my mother remains and she is in her old age now.

My question is, do the same rule that applies to real parents apply to adoptive parents also? Alhamdulillaahi I have always tried my best to be a dutiful daughter, but if I were in some way to make my mother unhappy, would it be a sin upon me, even though she is not my real mother?

Also, it is said that the only thing that will benefit someone who is dead are the du'aa from his or her children. I have always loved the father who raised me more than my real father, but I always include both of them in my du'aa (along with my mother). But since I'm not the real child of my adoptive father, do you think my du'aa would have the same effect?

I have searched Q&A for some time now, but haven't been able to find an answer to my question. If you have already provided the answer to my question, then I would appreciate it if you would direct me to the fatwa number.
Praise be to Allah.
    No one has any rights equal to the right that parents have 
    over their children. Allah has mentioned their rights alongside His rights, 
    as He, may He be glorified and exalted, says (interpretation of the 
    meaning):

    “And your Lord has decreed that you worship none but Him. 
    And that you be dutiful to your parents. If one of them or both of them 
    attain old age in your life, say not to them a word of disrespect, nor shout 
    at them but address them in terms of honour.

    24. And lower unto them the wing of submission and 
    humility through mercy, and say: ‘My Lord! Bestow on them Your Mercy as they 
    did bring me up when I was young.’”

    [al-Isra’ 17:23, 24]. 

    But that does not mean that you should not be kind to and 
    treat well those who were kind to you and treated you as a daughter, or that 
    you should not try hard not to upset them. Allah says (interpretation of the 
    meaning): “Is there any reward for good other than good?” [ar-Rahmaan 
    55:60]. 

    Your mother’s maternal aunt and her husband have treated you 
    very well and been very kind to you, so you should respond to their good 
    treatment in like manner, even if it is a kind word or good treatment to 
    your maternal aunt, and also offering du‘aa’ for them. 

    It is not essential for the du‘aa’ to be for one’s parents in 
    order for it to be accepted; rather if you offer du‘aa’ for any Muslim, that 
    is one of the du‘aa’s that are answered, as it was narrated that the Prophet 
    (blessings and peace of Allah be upon him) said: “A Muslim’s prayer for his 
    brother in his absence will be answered. At his head there is an angel who 
    is appointed, and when he prays for good for his brother, the angel who is 
    appointed says: Ameen, and you will have something similar.” Narrated by 
    Muslim, 2732. 

    So how about du‘aa’ for the one who treated you so kindly and 
    took such good care of you? That is more deserving of being answered. 

    Do not worry about a response or be distracted by thinking 
    about how effective your du‘aa’ will be; rather your concern should be 
    focused on making the du‘aa’ sincere and putting your trust in the vastness 
    of Allah’s bounty and the greatness of His mercy towards His slaves. 

    You should also remember that honouring one’s parents does 
    not stop when they die; you can still honour them by offering du‘aa’ for 
    them, honouring their friends and relatives, and fulfilling their promises. 

    Remember that your mother’s maternal aunt is also a maternal 
    aunt to you and her right to honour and kind treatment is great. 

    And Allah knows best.