Join Date: Mar 2010
Location: Ontario, Canada
Ah...now I understand. I don't think it will be easy to do a proper introduction if she's only there a few hours a day. However, what you're seeing is likely the result of just putting them together without an introduction.
Of course, you have to play the hand you're dealt. So, if she'll only be there a few hours a day for now, then I'd put her in a separate room when she's with you...preferably one that your cats are often in. That way, she'll start to get used to their scents when she's in the room and they'll start to get used to hers when she's gone.
After doing that for a while, I'd move to putting her in the room and leaving the door open a crack...feeding the cats either side of the door, etc. So, a typical introduction, except it will likely proceed more slowly than normal since she's not with you full time.
Alternatively, if it's feasible, you can suggest your Mom leave her with you full time and that you'll try to introduce her to your cats...but if after a few weeks to a month, things haven't improved, your Mom will need to find other options.