The family searched in vain for the toddler at Christchurch hospital and later posted a photograph of Mucad, smiling with Abdi, along with the caption: "Verily we belong to God and to Him we shall return. Will miss you dearly brother".
Abdi described his little brother as "energetic, playful and liked to smile and laugh a lot", confessing he felt nothing but "hatred" for his killer.
Zulfirman Syah and son Averroes
Alta Marie said her husband Zulfirman Syah shielded their son during the attack at Linwood Masjid.
Syah's brave actions caused him to receive most of the bullets and much more complex injuries than their son Averroes, she said.
"He is in stable condition following the extensive exploratory and reconstructive surgery he had earlier today.
"While he is still in the intensive care unit at this stage, he will be moved to the general ward whenever it is deemed appropriate - likely in the next day or so.
"While the road to recovery will be long, his condition has only improved since he arrived at the hospital yesterday.
"This afternoon he had a visit from the Indonesian ambassador, which lifted his spirits."
Alta Marie said son Averroes sustained minor injuries, including a gunshot wound to the leg and backside.
"He is traumatised, but we are all alive," she said.
"[He had surgery this morning to extract some shrapnel while checking for internal injuries.
"He is recovering nicely and has been cheerful while keeping the staff on the children's ward entertained with his talkative and energetic nature," she said.
"I am grateful that my family members are alive, as many lives were lost during these attacks. Please keep those people in your thoughts and prayers."
Alta Marie said the family had just moved to Christchurch two months ago.
Abdulrahman Hashi, 60, a preacher at Dar Al Hijrah Mosque in Minneapolis, says his 4-year-old nephew was among those killed.
He received a phone call on Friday morning from his brother-in-law Adan Ibrahin Dirie, who was also in the hospital with gunshot wounds. Four of his children escaped unharmed, but the youngest, Abdullahi, was killed.
The family had fled Somalia in the mid-1990s as refugees and resettled in New Zealand.
"You cannot imagine how I feel," Hashi said.
"He was the youngest in the family. This is a problem of extremism. Some people think the Muslims in their country are part of that, but these are innocent people."
Heba Sami, whose father was shot and injured protecting his children, told Gulf News that she lost five family friends, including a 12-year-old boy, in the attack.
Sayyad Milne, 14
Sayyad's father has spoken through tears of his "brave little soldier", who died at the Al Noor Mosque.
The Year 10 Cashmere High School student was at the mosque with his mother and friends. He attends every Friday.
His father John Milne said through tears: "I've lost my little boy, he's just turned 14. I'll get it together again.
"I haven't heard officially yet that he's actually passed but I know he has because he was seen.
"[I'm] keeping it together and tears are helping. People are helping. Just by being here, it is helping."
He said he was told Sayyad was lying on the floor in the mosque, bleeding from the lower parts of his body.
He said Sayyad had been a keen football player.
"I remember him as my baby who I nearly lost when he was born. Such a struggle he's had throughout all his life. He's been unfairly treated but he's risen above that and he's very brave. A brave little soldier. It's so hard ... to see him just gunned down by someone who didn't care about anyone or anything.
"I know where he is. I know he's at peace."
Milne said he has been carrying around a sign in Christchurch which reads "everyone loves everyone".
The principal of Cashmere High was going to visit the family soon.
"The community is shattered," Milne said.
"The Muslim community just don't know what to do, where to go, what's happened. They're finding it very hard to accept but there is so much support from so many different people, people who aren't Muslim. Support across the board.
"But we are the most beautiful city rising out of the dust. We will go forward. This won't bring us down. It will make us even stronger. United we stand, divided we fall ... the city is going to be a symbol of what it can do after it has been hit and hit and hit."
Milne's other son usually went to the mosque but had been on a school trip. His twin sister was at school when the attacks happened.
The family of Khaled Mustafa had also thought they had found safety in New Zealand after fleeing the bloody chaos of Syria only a few months ago.
But he too became a victim of hatred when he was shot while praying with his two sons, Hamza, who is now missing, feared dead, and Zaid, 13, who is recovering from a six-hour operation on his wounds at Christchurch Hospital.
Ali Akil, a spokesman for Syrian Solidarity New Zealand, said Mr Mustafa's wife and daughter, who were not at the mosque on Friday, were in "total shock, devastation and horror".
He added: "They survived atrocities and arrived here in a safe haven only to be killed in the most atrocious way.
"They were just looking for a safe place. Unfortunately we can't claim that New Zealand is a safe place any more."
Naeem reportedly died at Christchurch Hospital, after he tried to wrest the gun from the shooter at the Al Noor mosque. His son Tahla was also shot and killed.
Naeem was from Pakistan, where he had worked at a bank before moving to Christchurch to work as a teacher.
His brother-in-law Dr Khursheed Alam confirmed to ARY News that the pair had been killed in the attack.
Ansi Karippakulam Alibava, 25
Alibava, a 25-year-old woman originally from India, is among the missing.