Why did Iluvatar allow aule to create the dwarves

[Aiwendil]

Yes but did Iluvatur not want all creations on middle earth to be made purely by him and not inadvertatnly.

I don't think that either 1. Iluvatar wanted all creations to be made by him or 2. the creation of the Dwarves can be considered inadvertant. If 1, then what about the crafts of the Elves? Iluvatar certainly allowed the Teleri to build ships, the Noldor to make gems, etc. As for 2, the creation of the Dwarves was very intentional on the part of Aule. I think that because Aule did this with good will, Iluvatar offered a sort of grace to him and the Dwarves. I think we can take an Augustinian view of things and say that the important thing concerning Aule's making of the Dwarves was his intention rather than his action.