Susan shaved her age in later censuses.The 1900 shows her living in Mattoon, Coles Co., IL as a boarder.She's 22 & (supposedly) born Dec 1877. Per the 1900 census that Carol gave you, that's where Robert lived.Also, on the marriage info Carol gave you, she's 24 & it shows she was born in Fancher, IL.Fancher is in Shelby County.
Things to consider:
It's possible she's Ida M. below & that her parents changed her name or she changed her name or she was adopted.
The below Charles & John L. are buried in Dodge Grove cemetery, as is Ellen. (Other family members buried in Dodge Grove also)
Findagrave shows this for where they're buried.....
The marriage for John shows his parents as Robert Chaplin & Ellen Langford.
The marriage for Charles shows Robt. Chaplin & Lankford.
1880: Holland, Shelby Co., Illinois
James Lankford (head) 26 IL>TN>TN Farmer Mary Lankford (wife) 21 IL>VA>IN Keeping House Estella Lankford (daughter) 3 IL>IL>IL Laura Lankford (daughter) 1 IL>IL>IL NEXT VISIT: Robert Chaplan (head) 31 IL>*KY>*KY Farmer Ellen Chaplan (wife) 30 IL>TN>TN Keeping House William Chaplan (son) 8 IL>IL>IL Charles Chaplan (son) 6 IL>IL>IL Ida M. Chaplan (daughter) 3 IL>IL>IL <<<<< SUSAN? John L. Chaplan (son) 3 Months IL>IL>IL (Born in March) *Matches parental birthplaces in the 1900 census.
In 1870, James "Langford" is 14 & Elenore "Langford" is 20. Parents (assumably) are John & Lizabeth, both born in IL.They reside in Shelbyville, Shelby Co., IL.
In 1860, James "Lankford" is 6 & Elender "Lankford" is 11. Parents (again assuming) are John & Elizabeth, both born in TN. They reside in Township 9 N Range 5 E, Effingham Co., IL.
In 1850, Elender Lankford is 1.John & Elizabeth both born in TN. They reside in Effingham Co., IL.
In the 1930 census for Harry & Sue, there's 21 year-old Wayne Chaplin, nephew.Wayne belongs to Sue's brother, Roy. Roy lives with his father, Robert, in 1900.