To dream that you are a usurper, foretells you will have trouble in establishing a good title to property. If others are trying to usurp your rights, there will be a struggle between you and your competitors, but you will eventually win. For a young woman to have this dream, she will be a party to a spicy rivalry, in which she will win.
If your dream appeared a usurper dream about this to the fact that, having shown an unhealthy ambition, you will become a laughingstock. People in positions of responsibility, such a dream could presage a complication of working conditions, the deterioration of discipline subordinate employees.
I dreamed that someone from your household usurped power in the family and started to dictate strict schedule - it might say about the accumulated (perhaps only subconsciously) irritation caused by family relations.
If you dream that you were a usurper, then there will be problems with the design of any important documents. After this dream must balance their desire to their capabilities, or very high risk of publicly embarrass.