Thanks, Chris. Even the ILC "bio" states that its history is cryptic.
Check out the ninth post, in particular, on this thread on Rum Soaked Fist:
That's probably about as much as is known about a bagua connection.
Sam Chin, in various media and in person, talks about how ILC has significantly evolved since his move to the U.S. He acknowledges the art's history and connection to more traditional Chinese arts through his father, but puts a premium on presenting ILC as a modern, well-codified IP/IS system that does not directly owe its existence to any given predecessor art.