Birth Records from Parish Records

I'm new to this site so forgive me if my questions are answered elsewhere. I'm researching my ancestors who left Norway in 1855. Three children were born in Norway ....I've found the birth record of the first child in County Telemark, Bo i parish (1843).....but nothing on the other two children. So my question is ....is there another parish in close proximity to Bo that they might have used as well? The home town is Seljord . Thanks