Leonard's sister Maggie married into a branch of my Parker family that I recently discovered. It looks like Mary Bracken Miscall moved to California and lived with Maggie sometime between 1900 and 1910. There's a grave with the name Mary Miscall on it in the same cemetery as Margaret Miscall Parker, but the year of birth is wildly off from anything in any of the census records I've found.
It appears that Warren also ended up in California, John Joseph ended up in Seattle, and I haven't found Edward. There's an Edward Miscall in Nebraska in 1885 that matches up, but no idea if it's really him.