Using GDPR to ask for school correspondence

[Onesmallthing]

Hello
Does anyone have experience of accessing a teacher’s email correspondence with the other parent by invoking GDPR?
I don’t want to just ask the teacher for access to the comms - if I do it formally then the teacher is not implicated - she is simply complying with the law.
Needed for custody stuff.

You would need the other parent's permission for the communication between them and the teacher to be given to you

Thanks Pickled