Did I use the term incorrectly? A sibling comment is someone else’s comment that shares a parent comment, is it not? I’ve seen others use this term

I think that the confusion is with the word my. If you had said a sibling comment, it would likely have been immediately clear. Linking or quoting the sibling comment would avoid linguistic ambiguity altogether.

I see. I will try that next time

Are you your own sibling?

> sibling (n.) (computing theory) A node in a data structure that shares its parent with another node.

https://en.m.wiktionary.org/wiki/sibling

> share (v.) To have or use in common

https://en.m.wiktionary.org/wiki/share

> another (det.) Not the same; different

https://en.m.wiktionary.org/wiki/another

Being one’s own sibling is incompatible with the accepted definitions, so no.