The four key witnesses are Scott Guy's father Bryan, wife Kylee Guy, sister Nikki Guy, and other sister Anna - who is Macdonald's wife.
Macdonald has avoided eye contact with his closest family members so far.
Dr Chris Gallavin, from Canterbury University law school, said delivering a case in chronological order was quite rare. "This case will be particularly traumatic for the family as, of course, the family of the victim is also the family of the accused."
Auckland University law professor Warren Brookbanks says giving evidence multiple times is particularly harsh.
"It's not something one would want to happen, but sometimes those things are unavoidable in a criminal trial."
The trial before Justice France and a jury of 11 resumes tomorrow.