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.

Tell the truth. I love my niece.

i just recentlly started talking to one of my sisters after 14yrs of not talking to here. One of my other sister died from a drug overdose. I still keep this sister at bay

For one thing, you are aggravating the situation by continually telling her that you are talking with her daughter. Stop doing that - you're making things worse. Continue to communicate with your niece as usual.

You need to be more sensitive to your sister on this. She cannot choose who you talk to and who you can be friends with. That's your decision.

If your sister asks how her daughter is doing, you can say something like - as far as I know, she's doing fine. And then stop talking about it.

If your sister wants to choose this topic to fight about, you can tell her that you're sorry that she doesn't have a relationship with her daughter, but that doesn't impact how you feel about your niece. No one is winning here. Your sister is holding onto a grudge and is punishing her daughter. Your daughter, therefore, has no relationship with her mother. And you are caught in the middle. So, don't fuel the fire.