In Snow White and the Seven Dwarfs are the dwarfs related to each other or they are just diamond-digger friends that share the house?

The story only refers to the dwarfs as companions to one another. Furthermore:

16. Dwarfs: Dwarfs in symbology represent the underdeveloped and the unformed. They are pre-adolescent and not developed sexually. They live an immature and pre-individualistic form of existence that Snow White must transcend. (In the original story they are not individualised and Walt Disney by giving them names and personalities has destroyed their meaning in the story.) The dwarfs are also close to the earth (they mine for gold which is the incorruptible metal) and they represent the unconscious and amoral forces of nature. IR

https://www.surlalunefairytales.com/s-z/snow-white-seven-dwarfs/snow-white-seven-dwarfs-annotations.html