I cannot relate to this topic, but from what I have read in the books which tell stories during the regency period, it is the heir to which everything is passed on, including the properties, family heirlooms and also debts. All the younger male siblings either have to choose from clergy, army or gambling and making a fortune. Frankly this system is beyond my understanding. How can parents give one child everything and leave the others to their own resources is something I will never be able to grasp or accept.
As regards to this dp, I have no idea as to what is the role of the heir to the throne in this period. Other than being royalty and a public figure, what is their responsibility towards the society and public in general. But I would definitely not like being royalty and a celebrity with all the paparazzi hounds behind me 24X7, looking for any damn small thing in my private life to publish and make money. Or sometimes make things up and publish.
So to conclude, I pass both the options of being a royal heir or his sibling.