Litter training two kittens

Yesterday I adopted two 8 week old kittens.  One used the litter box three times yesterday, the other did not.  She disappeared behind my couch a couple of times, I am not sure if she peed back there.  I am assuming that she did, but have no evidence.  They are currently in my guest bedroom with two separate litter boxes, food water, blankets, toys etc.  I was wondering if I should put the untrained one in my bathroom with a litter box when unsupervised.  Should I keep them together?  I unfortunately work during the day, so I am not home to supervise and put her in the litter box regularly.  Im going to try an unscented version later today.  Everytime I put her in she jumps right out.  I was told she is the runt of the litter (if that matters)  I dont want this to develop into a habit and I worry since I am not there during the day it will be.  That being said, I work close to home and go home on my hour lunch breaks.  Thoughts? 

There is a product called Cat Attract

Here is a review of this product.

http://www.thecatsite.com/products/...ract-problem-cat-training-litter/reviews/4775

Great, Ill try that.  Is this something that I have to consistently use (assuming this works) or just until she gets used to using the litter box?

Kittens this age are not necessarily fully litter trained yet. She also may be reacting to her new environment. Putting her in the litter pan before and after meals helps.

I would put both kittens in the bathroom with food, water, litter pan, and toys for a few days until you feel confident that both are using the box. I would not separate them however.

Thanks. I do not want to separate them.  The whole reason I got two was so they would have a playmate.  My only reason for considering that is to know which one is having accidents, but I will keep them both in there until both are using it properly.  Thanks for the suggestion. 

Sounds good. You can bring them out to play and socialize when you are home to supervise. If you see one start sniffing or pawing, immediately put it in the box. Hopefully this won't take longer than a few days .

How big is the litter box?  You may want to use something with lower sides so the kittens can get in and out easier, like the disposable aluminum cake pans at the grocery store.