Tawdry Mystery Needs Investigators

My great grandfather, Amandus Sally Karlsen, was born in Barbu parish, Arendal on 10/14/1902. (Digitalarkivet: Parish register No. A5, dp pg. 45) His parents are Karl Karlsen (gift) who was apparently married to another woman and Amalie Berglund. I translated the comment to “Miss Tilla Andersen formerly Berglund, mother’s sister notified me of child 3/14/1903, the father ascribed” Others mentioned are Amalie’s sister and brother-in-law and Oskar Karlsen and Olevine Aanonsen presumably Karl’s brother and sister-in-law. I found Oskar and Olevine but I am unable to find anything on Karl, my family’s namesake. Can someone please help solve this?