Wladyslaw Lach
Wladyslaw Lach voted up dragonfly forty-six's answer
My sister has not talked to her daughter for 20 years. My sister gets upset when I talk to her daughter. She shows signs of anger. What can I say to my sister that lets her know I like her daughter, even though she does not?

If you feel you must I'd just be honest about it. Being that said daughter is at least over the age of 20, going forward I wouldn't talk to her about your relationship with her daughter after said conversation. At that point you could be rubbing it in her face which could anger her further.