About the Seven Fathers it is enough said, I think. But not for the female Dwarves. Of course there should be some female Dwarves from the beginning. Otherwise there wouldn't be a race of Dwarves.
But Tolkien wasn't sure how to include the female Dwarves, the spouses of the Seven Fathers. There were several different versions of it. (HoME XI, The War of the Jewels: Concerning the Dwarves) I will give a short overview over the versions:
- Iluvatar himself added a mate to each Dwarf. But in same look as the male Dwarves, because he would not amend the work of Aule, who created only male forms.
- Aule made at first One, the Eldest (Durin), than Six and than Six females, Then he rested and worked on the Seven Fathers. Then Iluvatar interrupted him.
- Aule made One and the Six and Six Females. Then he wearied and laid the pairs together
- Aule made Seven Male and buried them together with Seven Female as the Voice bade him.
- Aule made Seven Male and buried them together with Six Female. The Eldest rest alone.
Tolkien couldn't decide, which version was the best, so he let the Females unmentioned.