If you suspect you have a family friend in the family archives, note the pertinent details and then do a quick search locally. For instance, many of the family friends in our collection are young people. If you know their name and which ancestor they resemble in age, check the class rosters. Chances are, they are a school chum. If the friend is in uniform, you probably have an old army buddy. If they are older, check the local atlases to see which family groups lived nearby. Back before TV or computers, local neighbors frequently maintained close relationships. And don't forget churches! Many friends can be found in the member rolls.
I have not ruled out a family connection for Frank, but noting his young age at death (25) and the care with which someone stitched together his obituary, I have mentally categorized him as a possible friend relationship. In other words, I have him documented and he stays in the collection, but I will not spend an exorbitant amount of research time on him unless I find another clue that points him back into the family category. Of course, all of this advice is for those of us who are pressed for time and cannot spend full time hours on our genealogy research......with that being said, the historian in me would like to remind everyone that we are trying to tell a complete story, and those friendships could someday prove to be invaluable links to further information, or lead to a story that would knock your socks off!