Life, Organisation Association
The Lancelot and Gunther family agree to marry into each other. This agreement was made earlier but didn't become official until Dieter took the throne.
The agreement started in 1761, when Dieter convinced Miriam to get pregnant with his children. In 1767, Miriam had her 7th child with Dieter, and the last one. Once Dieter became king, he was quick to gather up Miriams daughters and get them pregnant, further connecting the new bloodline and the intermarriage began. Elda, Miriam and Dieter's daughter, married Indigo's son, and so forth. It didn't even have to be marriage, they just had to have children with one another.