It is true that some cats do NOT accept kittens at a young age (I have found it is especially females) but as they get older and bigger those bad feelings go away. So this is hopefully what might happen.
In the mean time, they should be separated except when supervised because we would not want any serious fights when no one is home.
I would definitely suggest more boxes. Tome will still have hers, but the kittens should have SEVERAL others. This might help them NOT use Tome's. (That in itself might help)
Will they be keeping BOTH kittens? Because this may help relieve the stress on Tome. WHY? Because the kittens will want to play, and if they do not have each other they will seek out Tome and this could prevent good relations (It also could help,BUT not likely given her personality)
If your friend wants it to work she will definitely need to give it time. And there is a real possibility that it still may not work, but without time, you can not be sure.
Best of luck to them.