I want to book a empty seat next to me. Is there a way to do that with points? How about through the UR portal on LY?
Every airline has a procedure for an extra seat, called "EXST", and the process varies between airline & booking system
Honestly, I've never done it. Just put the same name on two seats?
I am not a T/A but with a miles ticket there is a possibility they will cancel one of those tickets if they have the same name. They will think you duplicated it by mistake.
I seem to remember one airline recommending adding a middle name "X" e.g. John X Doe
I do not recommend this, and duplicates do get canceled, even if both are ticketed the airline can (and some even will) cancel one of those. And on international travel where your passport gets matched to the booked ticket you might have issues checking-in if not booked correctly