Im pretty sure that the first Kid Cutler whom John L. Sullivan trained to fight fight Jack Johnson(and lost by KO),
was the wrestler turned boxer Charley Cutler,
who was also the original trainer of Jess Willard I believe.
His brother was Monte(Marty)Kid Cutler best known as Jack Johnson's sparring partner around 1910.
There was a third Cutler brother who stayed a wrestler and never entered boxing.
I remember reading a newpaperarchives article dated c. 1930's,where it was about their reunion,not having seen the third brother for about 10 years.
Possibly more research needs to be done on this.