Does 'attorney of record' mean that only that lawyer is responsible for your case?

Can another lawyer within the same firm appear for the 'attorney of record' in a divorce case? I signed on with the head lawyer but somehow I have been working with the assistant and I noticed my paperwork with the assistant's name on it saying 'attorney of record'. When I questioned the assistant lawyer, he said it was just formality that the head lawyer was still in charge of my case. Aside from the initial appearance in court by the head lawyer, I have only delt with the assistant, who like I said now bears the title, 'attorney of record'. I am being charged for letters sent to the judge because the head lawyer is unable to attend meetings/ mediation but from what I see he is not the "attorney of record" for my divorce. Is it even legal to do that? I read online that  paperwork needed to be filed at the courthouse to change from one lawyer to the other? If that is correct, when were they going to tell me they changed hands? I have papers with the assistant attorney's name on them and others with the head attorney's name on them. Can the head lawyer just fill-in when he is not the 'attorney of record'? Can they charge me for letters the head lawyer is supposedly sending to the judge and adversary saying he cannot attend the meeting when he is not the'attorney of record'? I thought from what I read online that the 'attorney of record' stays with you until the end of your case or you decide to change to another lawyer. Is that true?