(U.K. ladies!!) help with national rail tickets

Me and my brother are due to visit our mum Tuesday, we was going to meet each other on the train Monday and get an open return to our mums as we're staying night and retuning next day, thing is my brother lives a train ride away from myself and I don't trust he'll be awake on time. I was wondering if he bought his open return on Sunday but stops at the town where I live will he then be able to travel on the next day to our mums or not? 🤔