second addition of yeast?

I've been aging an imperial stout for the last eight months. Last week I split it into two 3 gallon carboys, one with some coffee and a shot of bourbon, the other I left alone. I plan on bottling these end of April, but am concerned that they will not carbonate due to the fact that this brew was sitting on a basement floor in Minnesota for the last 8 months... Should I add a packet of yeast to this, what would happen???

Add 1/4 to 1/2 of package of reactivated dry yeast to the bottling bucket before bottling. Then that yeast will eat the corn sugar I assume you will also be adding at bottling and will carbonate the bottles.

if you added the yeast to the carboys now, I don't think much will happen because the initial yeast most likely ate most of the sugar. If anything, you would get a small secondary fermentation, but it would not carbonate the beer.