Okay so I think I follow.
Right now your recipes are set to target: Kettle, with 80% kettle efficiency (mash efficiency), with a postboil volume of 6.75 gallons, and a batch size of 5.5 gallons.
The best thing for the scenario of fermentables being added to fermenter is to use target: fermentor, and change the efficiency from 80% (kettle) to 65% brewhouse. 65 = 80 * 5.5/6.75.
This should keep the OG the same, you might have to make some small adjustments to using brewhouse efficiency instead temporarily, since currently the live version does not apply efficiency to late additions for sugar. This will be corrected soon in the update for late additions and improved gravity formulas.
Then you can set one sugar addition to kettle, which will increase the postboil gravity by 59.8 total points, and the OG by 48.8 points (accounting for 1.25 gallons of wort lost at kettle transfer).
Then set the other sugar addition to fermenter, which will increase your ABV as if the OG was 59.8 total points higher, without actually changing the OG.