From a dad that has and is still going thru the same thing. Let me give you some insight on what I have done, my pbfh ex would not put me on my sons papers for school, well I took it upon my self to contact the school and add my self to the contacts and what ever else that asked for my info, granted i have joint managing custody, with her having domicile.. Any who I just had to take it upon myself to make sure that my name and info go onto the forms and to the school etc.. myself, and not rely on her to do it, plus I aslo found out the teachers e-mail addy, and conference times, I started by e-mailing the teacher, and introducing myself, and briefly explaining the situation to her, then followed up with her by calling her during her conference time and talking to her about the situation..
Hope this helps out some...