The 1895 census for Multnomah County gives these Wallings, all in precinct 43, page 53 - they are listed separately in the index, so not sure how they are arranged on the page.
Also, there was a child of Nelson Walling, late birth entry in Yamhill County for October 17, 1890, I think that is the date of birth, not when it was filed. But there is also an estate record for a Nelson Walling in Yamhill County in 1885, unless he was just named in the record.
This is from the Oregon Historical Records Indexhttp://genealogy.state.or.us/
It looks like they had several children in the 1900 censushttps://familysearch.org/pal:/MM9.1.1/MSD2-FGG