Belgium's Princess Delphine finally met her half-brother King Philippe for the first time, following her successful legal battle to use a royal title.
The siblings enjoyed a "warm encounter" last Friday, the royal family's official Facebook account says.
The princess, who is 52, spent years fighting to be recognised as a child of former King Albert.
He admitted paternity in January. A court later granted her the same rights and titles as his children by marriage.
The decision was announced on 1 October.
A message issued by King Philippe and Princess Delphine said on Thursday they had met for the first time at the Castle of Laken the previous week.
"This long and rich discussion gave us the opportunity to learn to know each other. We talked about our respective lives and areas of shared interest," they said.
"This bond will further develop within the family setting."
Delphine Boël, an artist, won her court case on 1 October. According to the ruling, she and her two children can now hold the surname of her father, Saxe-Cobourg.
She will be entitled to receive an inheritance after Albert's death, along with his three other children - Prince Laurent, Princess Astrid and King Philippe.
Despite her new title, Princess Delphine will not receive any royal endowment. But Albert must pay nearly €3.4m (£3.1m) to cover her legal fees, according to local outlet De Standaard.
What is the background?
Princess Delphine's mother, Baroness Sybille de Selys Longchamps, says she had an 18-year affair with Albert before he was king.
Rumours first emerged that he had fathered a child with another woman after it was disclosed in an unauthorised biography of Albert's wife, Queen Paola, published in 1999.
The princess first alleged on the record that King Albert was her biological father during a 2005 interview, but it was not until he abdicated in 2013 - when he lost his immunity to prosecution - that she opened court proceedings.
The 86-year-old had resisted court orders to undergo DNA testing until he was facing fines of €5,000 per day for refusing to do so. In January, he announced that he accepted her as his fourth child after he had "learnt the results of the DNA tests".
Belgium has a constitutional monarchy in which the king plays a largely ceremonial role.
Who is King Albert II?
- Born in 1934 as second in line to the throne
- Married Italian Donna Paola Ruffo di Calabria in 1959
- The couple have two sons and a daughter
- Became king in August 1993 following the death of his older brother, King Baudouin
- With his constitutional role, stepped in during country's 2010-2011 political stalemate
- Served as monarch for two decades until his 2013 abdication