That isn't the correct Katie Sheehan in Springfield. Her mother was Mary "Mollie" Harris, b. 15 Aug 1870 in Selby Twp. Bureau County, IL, and died 6 May 1904 and is buried in Berean Cemetery, Westfield Twp. Bureau Co. IL. Her father was P.M Sheehan, I believe he was Patrick. The only thing I know of him is that on Mollie's grave it says: Mollie Harris wife of P.M. Sheehan.
Katie had one brother George Charles Sheehan b. 28 Nov 1892 in Seatonville, Hall Twp. Bureau County, IL. He died in 1963 in Kankakee, IL and is buried in Mount Calvary Cemetery, Kankakee, IL.
Katie is in the house of her grandmother Fannie (Frances) McKee Harris in the 1910 census, in Seatonville, IL. She is listed as a boarder. So I assume her father had already died as well. She married young - 9 Nov 1910 in Seatonville to James Lunn, a coal miner in Seatonville.
The Will I'm referring to is that of her Great-Aunt Bertha (McKee) Neill in 1949. She is listed as a grand-niece. It has that her and George Sheehan are the only children of Mollie Sheehan, deceased, the fifth child of Fannie Harris, deceased.
That gives you a little more on her.