add "department" in Address extrafields

Dear Team,

Actually GD extrafields for Address is as follow and i need to add one more information like “department”:

a:15:{s:9:”show_city”;i:1;s:10:”city_lable”;s:4:”City”;s:11:”show_region”;i:1;s:12:”region_lable”;s:6:”Region”;s:12:”show_country”;i:1;s:13:”country_lable”;s:7:”Country”;s:8:”show_zip”;i:1;s:9:”zip_lable”;s:13:”Zip/Post Code”;s:8:”show_map”;i:1;s:9:”map_lable”;s:18:”Set Address On Map”;s:12:”show_mapview”;i:1;s:13:”mapview_lable”;s:15:”Select Map View”;s:12:”show_mapzoom”;i:1;s:13:”mapzoom_lable”;s:6:”hidden”;s:11:”show_latlng”;i:1;}

I Need to add one more like “Department” after [ a:15:{s:9:”show_city”;i:1;s:10:”city_lable”;s:4:”City” ]

Like: s:11:”show_department“;i:1;s:12:”department_lable”

Thank you for your help

Sam