Michigan research today(yes I know that's not southern.)

Very productive day. I had gotten an email from Karren Salminen who is researching a William Buchanan. Karren went on to explain that she had a marriage record which showed that her William Buchanan must have married Allice Shallow before marrying her grandmother but that the age for William Buchanan was off by six yrs or so on the marriage certificate. I wrote explaining that Jim's Gr Gr grandfather Frank Buchanan who married a Julia Shallow had a brother named William and asked if Wm. Buchanan might have had a brother named Frank. I had not really done any research on who Wm Buchanan had married or what children he might have had. Karren replied that her grandfather didn't have any brothers. I received another email from Karren with a copy of the marriage entry which showed that this Wm. Buchanan's parents were John Buchanan & Ellen Lincoln. This meant that this Wm. Buchanan was indeed a brother to Frank as that was also Frank's parents' names. Then just below that it showed the name of Allice's parents. Allice's parents were also Julia Shallow's parents!! So two Buchanan Brothers married two Shallow sisters. I'd not had any luck with the census entries for the 1900 census for Frank's mother(she remarried) or Frank...but with this new info I was able to find census entries for the both of them and also for Wm. 's family. Allice never appeared in a census with her parents because she was born in 1883 and was living with Frank & Julia in 1900. Seems that by 1910 Wm's family had moved along with his Mom & Stepdad to Washington State but by the 1920 census Allice was widowed and again living with her sister and brother in law in Oakland Co. MI. Without having gotten a copy of that marriage I probably wouldn't have been able to find Frank and may have never pursued research on his brother William so I'm doubly in debt to Karren for sending me that info. I don't believe that this Wm. is the one which Karren was looking for but I do intend to try and help find him. I also want to know what happened to William Buchanan and family in Washington.