Simplify the following text for a Grade 8 native English-speaking person.
Original: They claim the principality of Orange on the basis of agnatic inheritance , similar to that of William the Silent , inheriting from his cousin RenÃ , though not being descendants of the original princes of Orange , and also on basis of the testament of Philips William , Maurice and William III .
Simplified: This way of inheriting is similar to the way William the Silent inherited from his cousin RenÃ . The claim to the title is also on basis of the testament of Philips William , Maurice and William III .