Yep, I know exactly whom you're talking about. Sadly, your great-grandfather is well-known in Yarmouth lore as the first ever train fatality in the county.
Frank (aka "Francois") was the son of Athanase "Migou" Dulain and Mianne Justine Mius. You can find his family on my Dulain site here:http://www.maplenet.net/~trowbridge/dulain/aqwg04.htm#4087
Athanase was born 25 sep 1824 and was a brother to my 4th-g-grandfather, Francois Dulain, b.14 Apr 1823.
I also found a posting on the Yarmouth message board which might also be referring to this family, though I'm not certain. It mentions a Jeanette Muise (could be Jane) who was married to a Dulong and had a child, Frances (could be Fannie?) in 1880. After her husband died, she remarried to a man named Richard Guinan. They also mention a connection to a Smith family:http://boards.ancestry.com/mbexec/message/an/localities.nort...
Your great-grandmother, Jean Muise/Mius, was the daughter of Nicholas Mius and Marie Marguerite Mius. I have information on her line, as well. Feel free to email me privately at trowbridge @ maplenet.net if you want further details.