As a start points (after a quick search on the internet):
Their son M Christophe GAILLY de TAURINES:
- C4. Mélanié Albertine Claudine Marie Ghislaine d’Ursel, Countess, * 1965, Md. 1993, Christophe Gailly de Taurines, * 1964.
- D1. Christophe-Hadrien Gailly de Taurines, * 1996.
- D2. Jean-Edouard Gailly de Taurines, * 2002.
- D3. Anastasia Gailly de Taurines, * 1998.
His sister Lelia Gailly de Taurines:
3i) Maria Karl Maximilian Georg Hubertus Graf von Khevenhüller-Metsch (b.Lugano-Sorengo 11 Mar 1959); m.Ossiach 5 Sep 1992 Lelia Gailly de Taurines (b.Neuilly-sur-Seine 28 Aug 1968)
1j) Maria Maximilian Johannes Christoph Alain (b.Klagenfurt 24 Sep 1993)
2j) Maria Franz Christoph Karl (b.Mistelbach 26 Mar 1995)
3j) Maria Sigismund Friedrich Georg Rudolf (b.Mistelbach 30 Dec 1997)
4j) Maria-Victoria Laura Christine Manuela Anna Viola (b.Klagenfurt 7 Jul 2000)
https://www.angelfire.com/realm/gotha/gotha/khev_metsch.html