A snippet from Wiki..
There is no record of Percy ever marrying. He does appear to have fathered two daughters by a Luise Verena Tschannen in Bern, Switzerland, for whom he made provision in his will, there being additional evidence in Percy being named as the father in the baptismal record of the elder daughter, Emelia.[2][3] It is unlikely that Percy married Anne-Marie FitzGerald, illegitimate daughter of Lord Charles FitzGerald, 1st