Hello Renie, You probably have an answer to this by now but just in case you need one, I will give it a shot. In the sentence you are talking about Changchang and that she will be going to Canada instead of staying at home. Using "with" her mother means that Changchang will not be traveling alone. Using "and" I do not feel is incorrect but it does alter the meaing of the sentence. It will now mean that both are going to Canada instead of staying at home. You are no longer just talking about Changchang. Using "as well" is not correct or generally used this way. Normally we would say, Changchang, as well as her mother, ... Again the meaning is changed. Now you would mean that both are going to Canada but not necessarily together. "With" is the correct word to use. I hope this helps.