It began with encouragement and small tokens of help in the mail, and continued through phone calls until finally in 1999, when the war was over, Sarah was able to keep a promise to visit the girl who had become her "sister".
Now 14 years later, memories of those terrible times have resurfaced as Sarah prepares to go back.
On the Holmes video, a distraught young Melisa tells of risking sniper fire and shelling to go out on the streets and collect water, and of difficulty obtaining food.
Melisa also gave interviews to journalist Cameron Bennett of current affairs show 60 Minutes, both before and after the conflict.
In the first of these interviews, Melisa tells of the death of her 2-year-old cousin from shrapnel after shelling; in the second, she tells of narrowly avoiding a marketplace bombing.
Melisa became, for many New Zealanders, the human face of the conflict, as people sent letters and cards and aid to a UNICEF appeal fund.
For Sarah, however, it had become more personal.
"During the war I would get packets of soup, prick a small hole in them to flatten them, and put them into envelopes end to end," Sarah said.
"Also fruit roll-ups, and cut them into the shape of the envelope for her little sister.
"Other things I managed to send were pain killers and water purifying tablets.
"The mail was sent to a church in Zagreb, and someone would go and collect them and bring them into Sarajevo for Melisa."
During phone calls, Sarah could hear shelling in the background and says "it was amazing to think they were eating Watties soup [that we had sent]".
"I wrote down the phone conversations I had with Melisa during the war and I could hear blasts and fighting in the background."
Melisa was responsible "for collecting the water for her family and would walk a very long way each day to collect the 25 litres that she carried up 11 flights of stairs to her apartment".
"Sometimes there was no water and it upset her to have to tell her family ...
"Even during her darkest moments, Melisa still maintained a great (often wicked!) sense of humour and we spoke about 'normal' teenage things like movies, music, plans for the future," Sarah said.
"I made a promise to Melisa during the war that when it was over, I would go and see her.
"I kept my promise and in 1999, I travelled alone to Sarajevo and was welcomed into the home and hearts of the Tolja family," an experience she describes as a real privilege.
"The love and hospitality I received from Melisa and her family was overwhelming, and they made sure I had a wonderful time; I was there for Melisa's 21st birthday.
Sarah witnessed the damage of the shelling and the trail into the city of refugees from Kosovo.
"It was 14 years ago but I'll never ever forget those things."
Sarah said she is going back "to keep another promise" and to "celebrate being normal adults with normal lives" as Melisa enjoys success in her chosen career and is engaged to be married.
Sarah says the people of Sarajevo "take nothing for granted and are proof that life is what you make of it".
