I love OnlyOffice along with WPS Office, but they're not "branches" of libreoffice at all, completely different products. You might be confusing LibreOffice branching from Sun OpenOffice.org/Star Office.
It's most likely that I am totally wrong, they just told me it was some "Latvian" branch, Lituanian, so I don't know. I might be confused overall but it's good someone knows. Thank you.