You didn't give the maiden name of Myrtle's mother, but it was listed on the CA dth idx as West. With that I found what may be a couple of her siblings, and her mother's given name, too. That is if the informant had the correct information.
Name: Lawrence Criswell Death date: 30 Jun 1954 Death place: Fort Sam Houston, Bexar, Texas Gender: Male Race or color (on document): White Age at death: 63 years 10 months 19 days Estimated birth year: Birth date: 11 Aug 1890 Birth place: Texas Marital status: Married Spouse name: Father name: W.J. Criswell Father birth place: Texas Mother name: Winnie West Mother birth place: Texas Occupation: Restauranteur Residence: San Antonio, Bexar, Texas Cemetery name: Ft. Sam Houston Natl. Cemetery Burial place: Ft. Sam Houston, Texas Burial date: 01 Jul 1954 Additional relatives: Film number: 2114215 Digital GS number: 4165563 Image number: 2955 Reference number: 31804 Collection: Texas Deaths, 1890-1976
Name: Algie Raymond Criswell Death date: 01 Apr 1946 Death place: Austin, Travis, Texas Gender: Male Race or color (on document): White Age at death: 62 years 10 months 10 days Estimated birth year: Birth date: 22 May 1883 Birth place: Spinkle, Texas Marital status: Married Spouse name: Gertrude Father name: Will Criswell Father birth place: Unknown Mother name: West Mother birth place: Unknown Occupation: Lumber Residence: Austin, Travis, Texas Cemetery name: Fiskville Burial place: Austin, Texas Burial date: 03 Apr 1946 Additional relatives: Film number: 2218357 Digital GS number: 4030540 Image number: 70 Reference number: 19868 Collection: Texas Deaths, 1890-1976
There are two females named Criswell also buried in the Kemp Cemetery. On the Kaufman Co, TX GenWeb site there is a Bible record -- W.C. Criswell md S.A. Spence [someone added names of Will and Sara Catherine.] Then on Death Page -- Kate Spence Criswell died 1912 [added information Sara Catherine] and that matches death date for Kate Criswell buried in Kemp Cemetery.
The other lady in Kemp Cemetery is Mrs. M. C. Criswell and this may be her:
Name: Martha Caroline Criswell Death date: 23 Aug 1933 Death place: Eustace, Henderson, Texas Gender: Female Race or color (on document): White Age at death: 77 years 8 months 2 days Estimated birth year: Birth date: 21 Dec 1855 Birth place: Miss. Marital status: Widowed Spouse name: W.C. Criswell Father name: Hally Father birth place: Miss. Mother name: Easily Mother birth place: Miss. Occupation: Housekeeper Residence: Cemetery name: Kemp Cem. Burial place: Burial date: 24 Aug 1933 Additional relatives: X Film number: 2115618 Digital GS number: 4166772 Image number: 1168 Reference number: CN37495 Collection: Texas Deaths, 1890-1976
Now, Wm C. and Martha C. are on the 1920 census in Henderson Co, TX.
This is just bits and pieces and some may not fit.