I know that when we have students transfer to a new school, the request is made from the new school and we fill out the report cards, etc and send them on....so, this might be out of moms hands unless she is withholding the old school info (which might not be possibly since so many things are available on the internet now for districts-all password protected of course) like where he attended etc....
I am brand new to this school and both my teaching partner (new too) and I decided we wanted to NOT look at old records to give each child a brand new start. In some cases, we were pleasantly surprised to learn that what was once considered a "problem child" (after last years teachers began sharing or parents began tellling us what trouble there was the previous year) was not any more.
However, we do have one child that has serious psych problems and this info was indeed shared and valuable to us. Our behavior program for him is slightly different than the rest of the class and we have certain warning signals we look for in his behavior that needs a caring, yet, firm handling. If we had not known this, I could only imagine the frustration on all our parts.....which, in turn, hinders the learning process.
Anyway, I think sharing the records is a good thing but both parents should be involved in any kind of issues that need to be addressed or possibly, behavior program that might be involved (actually, required by law)
Does your child have an IEP?