Hi Jill.
I bonded Lorna's Georgia, Freddie and Freya for her, although that wasn't due to bereavement. It's was not much more work than a pair to be honest, it just took a while to be sure that it was going to work before they went back home.
I am about to try and bond another single with an existing pair of boys (single lady lost her sister last year) but am not any more worried than I would be for a pair in this case. I do think that it depends entirely on the bunnies. I also think that it's much harder bonding your own bunnies because you are more stressed about it and I firmly believe that your bunnies pick up on it.
I'm sure someone will have full on experience with a recently bereaved bunny - will be an interesting thread to watch.
Helen