Came Friday, Gone Saturday

Friday trespassed to our house on April 2, 2010, which was not just any Friday, but Good Friday. Thus, we called her Friday. I found her under the Kenari avoiding every spot from the pearly whites of Zippy. Zippy can kill! I rescued her into the house and kept her in the bathroom while I went to work. I had no idea where she came from. The next day, another puppy came but this one was badly bitten by Zippy and we had to send her away. After a few days, I had a feeling that 2 doors away there is a bitch with 2 puppies. I thought maybe that's Friday's mom. One day I did let them meet, I could sense the reaction from both was different from any puppy dog meet.
Friday was different than many puppies we had. She was quiet, even you tie her up or put her in a cage. If she makes noise, means she needs to potty. She has responded well to potty, as well as several other commands like "finish it", "go back there", play fetch at only 4 months old. There were many tricks which she did, photos are in the Facebook. When I sit on the floor, she would curl up with me. And if i am on the chair, she loves sitting on my lap. At times, she would jump up to me when i am sitting and can land herself well. She loves to go on car rides, and she takes a chair and will be very still, just like Zippy and a passenger.
Last Saturday, dad forgot to tie the 3 dogs. Opened the gate and out they went. In fact, before I went to office, I tied up Friday behind. Not sure why dad untie her, took the chain to the front. Zippy & Koala came back but Friday didn't. I have searched the neighbourhood, but nothing. Even went with Zippy and brough Friday's toy along. I am not sure, if Friday ran to the "mom" and the worker just locked her up.
She is smart, and I believe that she can her way back to our house. But if she really run away, where could she go? And why away from us? We have treated her very nicely. She bullies Koala a lot. Only Zippy is jealous of her. We gave her food. I just don't understand.