To Do Good or Not To Do Good

I was divorced and dating a man I was completely enthralled with and he with me. The fly in the ointment was his mother. I tried putting balloons on her mailbox for her birthday sending her a car detail coupon, a gift certificate to her favorite type of candy, etc. Nothing persuaded the mother to move to my side. Then the mother came down with colon cancer. I visited the mother in the hospital. She said to me, “You have been nothing but nice to me, but I still don’t like you.”
The relationship between the man and I ended and his mother died.
I later married and am now in a similar situation with my husband’s sisters. My husband’s first wife was not nice to him. However, his sisters never saw how the first wife treated him. Consequently, the sisters favor the first wife over me.
Motivation speakers tell you that no matter what you do 10% of the people will never like you. The Scripture tells you that for the Christian to know to do good and not do good, it is a sin. So the $64,000.00 question is do I do good and sow blessings knowing the sisters of my husband are not going to like me, accept me, or even treat me as family?