HOFFMAN - WILM - Ambassador

Sorry if this is a duplicate post.
Looking for descendants or ways of connection to the following.
My grandfather, FREDERICK WILHELM VIKTOR FRANZ HOFFMANN, born February 1859, possibly in Berlin emigrated to Canada 1885. His brother WERNER WILHELM HOFFMANN came in 1889. Their father, HERMANN EDMOND TASSILO HOFFMANN was a Prussian Ambassador to Queen Victoria during 1800's. Their mother was CLARA WILM. The Ambassador married twice and had 17 children. I have some photos and names in pre 1885 album.
Any advice for me on how to find information on the Ambassador? I do not know what city they lived in, I only know they spent childhood on the Baltic seashore and were Prussians. An older brother, also named Hermann, was a Ship Captain, Burgermeister, and Police Magistrate. Help me find them?
April in Canada