There is a J. Ralston here from 1856 till 1857, but this is before the cdv period, so the photographer here would have been Peter. The font and form of lettering was used in the very early 1860s by others such as Bowman, Urie and MacNab, and the cards were probably supplied to them by a third party.This early period is supported by the full skirt and ears concealed by the hair and bonnet of the lady in the first cdv, a fashion of the late 1850s. The younger lady is dressed in a more contemporary fashion.
This second cdv looks like a 'Gem Tintype', a very cheap form of miniature photo involving multiple images from one exposure. However, this is in fact an albumen print, produced for some reason to resemble the tintype. The form of the reverse design suggests a date in the mid to late 1860s