Othon Henri D' Ongnies
Othon Henri D' was born about 1718.  He died in 1791.

 Marie De Merode
Marie De was born on August 27th, 1721.  She died at the age of 48 on December 1st, 1769.

 Marie D' Ongnies
Marie D' was born on September 20th, 1760 in Brussels, Belgium.  She died at the age of 81 on August 4th, 1842 in Brussels, Belgium.