F&S wasnt a company. It stood for Field and Staff which ran the regiment. I have some things in books that I can look in regarding the name you gave. I take it you have military and pension records for your ancester. If you got them from the nara forms available from the national archives, speaking from personal experience, there are other records available from the national archives. There is a link at the top of this webpage for a private researcher that would have acsess to looking for those records. Usually the higher the rank, the more there might be. I used to get records myself but travelling to the National Archives from Michigan at todays gas prices leave that a memory