Is there a gender-neutral version for expressions like "sister site"?

I have recently seen "sister site" being used and I am wondering if there is a gender-neutral equivalent for it.

In my native language (Romanian) expressions like "brother X" or "sister Y" feel natural because the language is gendered and there is a gender match (although the "sister" tends to be used more often despite the noun gender).

I am thinking of sibling as a replacement, but I am not sure about it.

Question: Is there a gender-neutral version for expressions like "sister site"?