50/50 custody in the military

Hello!

My husband is going to be leaving for BMT soon. We currently have 50/50 custody, week on week off, of his son. Has anyone been in this situation? How can we maintain the 50/50 custody? Would year on year off work? Also, while my husband is in BMT would the schedule stay the same or would he have to stay with his mom the entire time? He has siblings here and is more comfortable at our house so I want to make sure that we keep things consistent for him and he doesn’t have to stay at his moms where he is alone and feels out of place but at the same time not wanting to take any time from his mom.