Thanks Karen.
I half-slept in the next room, setting my alarm for every 2 hours to check on them. I didn't need the alarm as it turned out as I kept getting up to check anyway. They were always in separate corners, though were in different parts of the pen each time (nobody keeping to the same corner as 'theirs'), no sign of animosity.
By this morning Elijah would run over for a treat and Erin joined him. Their little faces squished together, no animosity but not really bothering much with each other. She kept either grooming him or asking him for a groom and then moving away when he wasn't keen. I'm happy to go to work and leave them though. (Not happy to go to work you understand as I will be clock watching all day as per usual) but confident that my bunnies will be okay in each others company.