In A) I modified .git/config to be as follows:
$ cat .git/config
[core]
repositoryformatversion = 0
filemode = true
bare = false
logallrefupdates = true
[remote "origin"]
fetch = +refs/heads/*:refs/remotes/origin/*
url = https://github.com/chad/gitjour.git
[branch "master"]
remote = origin
merge = refs/heads/master
[remote "lach"]
url = ../u
# fetch = +refs/heads/*:refs/remotes/origin/*
fetch = +refs/remotes/origin/*:refs/remotes/lach/*
My final change, for reference, was updating [remote "latch"] section with:
url = https://github.com/lachlanhardy/gitjour.git
fetch = +refs/heads/*:refs/remotes/lach/*
Appears to work with git fetch --all
and finally followed by git gc