Sometimes, you've got a branch of a repository that was branched in a way that SVK can't find the branchpoint easily. (Like someone used /svn add/ instead of /svn cp/)
To make use of svk's intelligent merging features, you can make use of the post-0.12 feature "svk smerge --baseless", or tell svk about the branchpoint manually, as described below.
Assume your mirrored repository is mirrored as a "toplevel" called "remote-repo" in svk. It has a standard svn repository layout:
//remote-repo/trunk //remote-repo/branches/1.0 //remote-repo/branches/1.1
1.1 was incorrectly branched from 1.0 by doing a manual copy and an "svn add" as of revision 409 on the remote repository
You have a local branch of 1.1 at //local/project-1.1
1. Identify the UUID of the local copy of the original repository
svk pl // |grep remote-repo
You'll see
svm:mirror:e417ac7c-1bcc-0310-8ffa-8f5827389a85:/: /remote-repo
Now, tell svk about the branchpoint
svk pe svk:merge //local/project-1.1
Add the line
e417ac7c-1bcc-0310-8ffa-8f5827389a85:/branches/1.0:409
Now you can safely run
svk smerge -C //remote-repo/branches/1.0 //local/project-1.1
When you mergeback, everyone else will be able to as well.