Why look for witnesses when the name of the parents are available? Caroline Julie - parents carpenter Lars Amundsen and Maria Ingebretsdatter, living at Ruseløkbakken. Anton - parents carpenter Lars Amundsen and Berthe Marie Amundsen (= most likely Ingebretsdatter).
Yes I see the parents - but since the mothers last name was not on the record the same way I was trying to confirm the relationship any other way I could think.
When they married Sept 5 1834 they were living same place as when Caroline Julie was born, - Russeløkbakken, last record on left page. Bride Berthe Marie Engebretsdatter.
When Caroline was baptized the mother is Maria Ingebretsdatter.
Another sibling Carl August, born Jan 1 1841 6th record right page. Mother Berth Marie Ingebredtsdatter - they were living at Ruseløkkbakken.
Another Caroline was born Sept 1 1837, 9th record left page. Mother Berthe Marie Ingebrethsdatter - they were living at Ruseløkkbakken. (Maybe Caroline Julie died before 1837?)
Their first child Andrine born Oct 21 1834, 1st record left page. Mother Marie Engebretsdatter - living at Ruseløkkbakken. (In the Ministerialbok Andrine is said to be born Oct 5, witnesses are the same, but again the mother is named Marie Ingebrethsdatter.)
If you don't find the confirmation records I believe you can trust they were all siblings.