Food manipulation is often done, even by humans, to keep BG on an even keel.
You just have to remember that food will not keep numbers up high that long... in a couple hours, if Lucy was on a downward mission, you may see her numbers drop a bit once the food wears off.
It is an option though, so see how she does today and where she ends up tonite.... maybe you can mover her back in time and also reduce dose if the numbers agree.
It's tough to know so far ahead, but having a couple options/plans on how to proceed prepares you for ps time.
See if you can test around +11 again and then ps number will let you know which direction Lucy's wandering.