Found a little cheat for creating break lines in dimensions. Click the dimension, right click change object type. Select lines, and un select 'delete original'. Move the original dim to one side, and put into hide. Draw a small polygon at the break point. Use the trim curve tool to trim the converted dim at desired position. Put polygon into hide.

If you then update things, at least you have original dim to work with.

The result looks pretty good. See attached image