I have the same issue. My PDM is set for 70 mg/dl as the minimum BG for calculations. When I am low before a meal, I want to be able to record what I eat and also bolus. If I just want to record carbs to counter act a low, I do what Bradford does. For the other issue, I do varying things because I haven’t found the best option yet.
I have upped the BG reading to 70 so I can bolus. I have stopped that, because it adds a false reading and there is no way to delete a reading from CoPilot.
Sometimes I eat and then wait for my BG to rise, retest and bolus. I don’t think I get accurate calculations from that.
Sometimes I will enter a BG of 70 and let the PDM do the calculations. Then I cancel and do the following manual calculation: Actual BG reading divided by 70 (fake reading) multiplied by the calculated bolus for 70. Then I manually bolus for that amount. That seems to work. My CDE is OK with that calculation.
Lately I do the calculation manually. I divide the number of grams I am eating by by my insulin to carbohydrate ratio. (I use one ratio for dinner and another for the rest of the day.) Then I manually calculate the negative correction by subtracting my BG level from my lower target number and dividing by my correction factor. I then subtract the correction from the number of units needed for what I am eating and bolus for that. There is a risk of hypoglycemia in doing this. My CDE told me the minimum for bolus calculations is a safety to prevent hypoglycemia.
Maybe some day I will figure out the best way for me.