So, you are saying your own Walter Columbus Finn is not the son of John Wesley Finn and Mary Jane Dowell.
According to the familysearch the John Wesley Finn -- that was the father of the WT Walter Columbus Finn -- was born 1864 died 1940 and was married to Martha Francis Kerbaugh (Illinois Death record, bur in Illinois)
The John Wesley Finn listed on WT is born 1848, KY died 1939
The stardard would be to collect the birth / death record of your Walter (available at familysearch) and the records of his father (at familysearch) and mother (at familysearch) ... admitted this will take some time
I have placed on the WT profile the census years / places that Walter resided in Illinois, and I have placed also the URL for Walter over at familysearch. If you have not yet used familysearch some time may be needed to experiment. There ARE SOURCES given for Walter and his parents and Walter's wife and for the children. Each person will have their own page there and their own sources etc
THESE SOURCES ARE FROM THE ARCHIVES OF THE CIVIL AUTHORITY, records from various govt including Illinois - there's no "familytree" stuff involved. Some have images you can examine.
With your evidence in hand you can approach the PM of the misplaced Walter.