Originally Posted by SapphireParure
I often wonder if non adopted can be raised to Royal Status? Seems to me like it has something to do with The Royal Letters Of Patent.
If, by royal status, you mean being in the line of succession to the throne, then the only way to give such status in the UK to an adopted child would be an act of Parliament as it would involve a change in the law of succession. That would also have to be agreed by the parliaments of the other Commonwealth realms whenever necessary in each realm's own domestic law. The Queen could, however, give any title to an adopted child, or even an HRH style, by Letters Patent only.
In the aforementioned case of Jean Baptiste Bernadotte, the Swedish parliament passed a special law, the Act of Succession of 1810, to establish a new dynasty and a new order of succession. That act, with a major revision in 1979, is still technically in force in Sweden today.