I’m trying the demo version of your grammar checker. I notice when I cut/paste the text to be checked, the Grammar Checker removes all additional line feeds and when I paste the corrected text in the original document the line feeds are different.
Is there a way of turning off this feature and have it leave the original type and count of line feeds unchanged?

The Grammar Slammer text box has few features so that it would be compatible with as many editing and word processing programs as possible. It does not directly strip or change any characters other than those it replaces or inserts. There are no adjustments of the kind you are asking about that can be made with Grammar Slammer.

You may want to experiment with the “Word Wrap” feature on the editor or word processor you are copying from. For example, it may be necessary to disable the word wrap before copying and then resetting it once you are done.