So I guess you can't...
When I am editing my writing and I jump into the middle of a pre-existing paragraph to take off from a phrase and then carry it off in a different direction than I had, it is simpler to use OVR to just plow through the rest of the paragraph as I am typing.
The overtyping only removes the sentences as I replace them but leaves the rest of the paragraph intact in case I decide to use it. I find it less confusing than typing and having the old material just pile up. Personal preference.