So sorry to hear about this difficult situation. It is good of you to remain involved in his care, as this can help him to maximize his long term prognosis. I recommend that you discuss your concerns with his doctors
. With regards to the specific question about lip biting, it depends in great degree on the amount of cognition that he retains. If this is a sort of tic that he is doing in a near unconscious fashion, then it may be necessary to brace his lip up in a fashion so that he can't bite it. Bite blocks and other things like that can be uncomfortable in some situations, but can prevent the need for surgery
to repair the significant trauma that he could be causing to his lip with the repeated bites. Some directed therapy against the muscles of the jaw could also be helpful, but may be more difficult to titrate appropriately. It is also important to know if he takes his food by mouth or uses a feeding tube, as that would affect the surgical options or other treatment possibilities. Obviously, this is a hard question to answer, and one that you will need to discuss with his doctors. Please speak with his doctors about this.