The established hymnal formats since 1861, when the Church of England published the first edition of the hymnal Hymns Ancient and Modern, has been to include music for the melody and harmonies, typically in four-part harmony (Soprano-Alto-Tenor-Bass), together with the verse materials. Therefore, the hymns published in the hymnals collected by David's parents contained such four-part harmony arrangements intended for congregational singing.
The three hymn harmony parts (Alto-Tenor-Bass) typically included with the melody, tend to follow a pattern of being easier for congregations to follow. While that facilitates the singing of 4-part harmony by less musically trained congregations, to some extent it also produces an effect that might be described as "sounding like church hymns."
While none on the hymnals used contained the additional part known as a descant, several descants were later obtained from the arranger Mr. Whitmill, and used in Phase II. (There is a discussion of descants under Phase II.) As an easy cross reference if you want to immediately read that material, you can click here on Descants.
In the process of recording Hymns and Songs for Living, Ms. Gerber-Salins extended her role as producer on some of the hymns, and created duet harmony parts other than the alto harmony part published in the hymnal. Ms. Gerber-Salins extemporaneously created those new harmony duet parts out of her head on the recording for those hymns' duet accompaniments. Her vocal harmony arrangements add variety and harmonic listening interest for those accompanying duet parts.
WHAT ABOUT DESCANT ON CHRIST THE LORD IS RISEN TODAY? IS THAT EXTEMPORANIOUS OR PUBLISHED? IF EXTEMPORANIOUS, WHO SHOULD BE CITED, DOROTHY OR HEIDI?
These gems are scattered throughout the album.
As of 2020, the vocal hymn harmony parts extemporaneously created by Ms. Gerber-Salins [and Dorothy Gerber?????] are not written down, and thus only exist on this recording. Whether Ms. Gerber-Salins may chose to document and have the harmony parts she created available is unknown. It is also unknown if or how she might chose to make them available.