Grieving Rat / Introducing New Baby Rat

Question
We had two female rats, one of which had a very large tumor and was rapidly declining.  The younger of the two females is the surviving rat.  She has only been with the older rat, who passed away last night.  Earlier in the week, I got a new baby female rat.  She has been kept in a separate cage, but has been held with the two older rats over the last few days.  Now that the older rat has died, her cage mate seems listless and unresponsive.  I've read that rats go through a grieving process just like we do, but I'm worried about her.  Should I try to speed up the introduction process to get the baby rat and the surviving rat in the same cage?  Any help you can offer would be helpful.

Answer
I wouldn't speed it up; however if they get along outside the cages and you've already cleared her from any quarantine process there is no harm in cleaning the cage well and introducing them now. If the cage mate is unresponsive to her, that's fine; however if she gets irritated with the baby, she needs more time by herself or may not take to having a baby around at all. I'm very sorry for your loss.. I wish you the best.