How to merge SVN branch back into trunk

I have SVN respository with master directory lbserver containing trunk and branches/imext directory. I want to merge the imext branch back into the trunk. If I open lbserver/branches/imext/lbserver.xcodeproj and click on Source Control menu, I see:

Working copies

imext - Y trunk >

lbserver - Y >

Create working copy...

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If I open imext pop-up menu, "Merge from Branch..." is available, but "Merge into Branch..." is grayed out. If I click on lbserver - Y the only option is "Configure lbserver..." I am mystified by the configuration panel that appears. It shows correct master URL for repository, and shows both trunk and imext under "branches" tab. I don't see what I am supposed to set here so that lbserver is "configured."


If instead start by opening lbserver/trunk/lbserver.xcodeproj, then I see only "lbserver - Y > Configure lbserver..." under Source Control menu.


Anyone know how I get XCode 8 configured so I can either "Merge from Branch... imext" in the trunk project, or "Merge into Branch... trunk" from the imext proj? I would like to see all files that have changed, and review changes before merge, like doing a Commit.