Adams Co IL was formed 1825 from Pike Co.You might look into any STEWART etal who would fit the profile, and resided 1830-1850 in either of these Cos.Check deeds for these Cos....David SEARLES may have purchased property from a STEWART relative...you never know! Marriages took place at the home of the bride, so Adams Co would be the best place to start. Myra was b IN [Ia on census indicates Indiana, not Iowa...folks are used to current abbrev of IA, but this not the case on the census...enumerators usually wrote Iowa in it's entirety, as it is short word.]
I noted John MC CONNELL and Myra SEARLES shared a home 1850, but 1860 Yamhill OR, except for Lucinda, everyone bears the name of MC CONNELL.Did they marry before, during, after trip to OR?I see she d 1870 Douglas Co, so way too early for a death cert.
Newton evidently didn't survive, and why is Fedis in Sonoma CA?Have you been able to follow up with her? You've been working on this a long time....sometimes it's best to put some people to rest.