The dating clause of a charter dated 1 Mar 899 records “rex Adefonso in Obieto et comite Munnio Nuniz in Castella et comite Gundissalbo Fernandiz in Uurgos”.
Conde en Burgos. His letter dated 912 to the town of Brañosera confirmed the rights granted by his paternal grandparents whom he names. He built the castle of Lara in 902.
Conde en Castilla: the dating clause of a charter dated 1 Sep 912 records “Garsea principe in Legione et Gundissalbo Fernandiz in Castella”. The Annales Complutense record that “Gunzalvo Fernandez” populated “Cozca et Clunia et S. Stephanum” in 912. He is last mentioned in Castile in 916. He may have been banished to Navarre from 920 to 930, a "Gundisalvus comes" witnessing royal Navarrese documents during this period, although if this is correct it is surprising that his wife did not accompany him, established as she was in the castle of Lara during that time. "…Nunus Guter, Lucidus Vimarine, Didacus Federnandici, Gundisaluus Betonice...Gundisaluus, Guincaluus Ferdinandiz, Federnandus Ansuriz, Gudesteus…" subscribed the charter dated to  which records an agreement between the bishops of Lugo and Santiago “pro commissos Prucios et Visancos”. “Gundesalbo Fernandez...” witnessed the charter dated 27 Jun 931 under which Alfonso IV King of León donated "Uilla Frida...usque in flumen Aslanzon" to San Pedro de Cardeña. "Gundisalvus Fredinandiz comes" witnessed a 932 donation, signing immediately after King Ramiro II and before "Fredenandus comes" (presumed to be Fernando González), Pérez de Urbel suggesting that this is the same person as Gonzalo Fernández de Lara. 1