Hope some of this is new information:
1925 Iowa State Census - Onslow
Caroline MacKrill age 78 born OH father: Wm. Holt b KY mother: Elizabeth
Nichol born OH
Etta Brown age 53 B IA father J Z. Mackrill b OH mother: Caroline Holt b OH
Joel and Caroline married
Wm Holt d 3/14/1891 age 75 , South Mineral Cem., Wyoming Twp, Jones Co., IA
Marriage Book E
#2676 Bertis C. Mackrill b Onslow married on 11/27/1889 in Scotch Grove Helen
Estella Sinclair b Scotch Grove father: A. Sinclair mother: Mary Ann Nelson
#2774 Leverett E. Brown born Onslow father: Emerson E. Brown mother: Gratie
Aubie married on 5/7/1890 Etta B. Mackrill born Clay Twp.
Marriage Book F
#4143 Joel Z. Mackrill, Jr.b Jones Co. married 1/16/1898 Wyoming Emma K.
Allen father: Anson E. Allen mother: Catherine E. Knight
#4002 William A. Mackrill b Onslow married 5/9/1897 in Onslow Margaret A.
Reade b Onslow father: Wm Reade mother: Emily Krouse
There is also a Samuel R. Mackrill in the area. And a Hannah (MacKrill)
Reyner. Both of these individuals appear to be the same age as Joel Z.
Jones Co. Lookup