Estranged family members and kids

My husband and I are expecting our first child in February, and it has gotten me thinking about what (if any) obligation I'll have to them, once they're older, to connect them with my estranged sister.

Long story short, I have a half-sister who is 15 years older than me (she's almost 50 y/o), and we haven't been in contact for over 10 years. My parents have been estranged from her for even longer. Based on my experiences with her before we stopped talking, I think my sister is an undiagnosed narcissist.

Once they're old enough, I plan on telling my kid that I have a sister--I do think it's their right to know what blood relatives they have. I won't badmouth her, but, if asked about the circumstances, I won't sugarcoat the fact that my sister was the one to cut things off (under crappy circumstances) and that I have no interest in rekindling a relationship with her.

I have been wondering lately what the heck I'd do if my child expresses an interest in wanting a relationship with my sister. She's not a dangerous person, so there is no reason to forbid getting in touch with her... but I also don't love the idea of making the connection on behalf of my kid and opening the door to having to communicate with her again.

I know this could all be a moot issue... my child could have no interest in getting to know my sister. But it's a possibility, and I'm curious how other parents have navigated similar circumstances with their kids.