The judge reviewed a pile of petitions from battling relatives Thursday.
The children's father, Bruce Beresford-Redman, is detained in Mexico as a person of interest in a murder investigation. Their mother Monica is the murder victim.
Thursday, Judge Mitchell Beckloff declared: "They have lost both their parents. It is important that they have something stable and consistent and regular."
The judge heard arguments on competing requests.
Bruce Beresford-Redman phoned the judge from Mexico and made his wishes clear. He wants his parents, David and Juanita Beresford-Redman, to be temporary guardians for the two children.
"That David, the grandfather, is somewhat an angry man. He has demonstrated that in front of Alec after he broke a glass," said attorney Trish Phillips, who is representing the sisters.
The sisters question the grandmother's strength. Juanita, 73, reportedly has lupus, and is tired and often sick.
Meantime in Mexico, the investigation drags on.
The body of Monica was found strangled and dumped near a sewer. A resort employee reported hearing the couple argue.
According to Monica's family, the couple had gone to the resort to try to repair a troubled marriage.
Following Monica's death, the children's nanny made a declaration to the court. She said Monica told her that Bruce wanted to take out an insurance policy before the trip to Cancun.
Part of the declaration of Maria Beatriz Oaxaca, the nanny, reads: "She thought it was strange since they had never taken out insurance policies before any of their other trips and said it made her feel like her life was a soap opera."
Ultimately Judge Beckloff decided to extend temporary guardianship to the grandparents.
He stressed that this was not a family law case, which would define permanent terms. It is a probate case. And there would be a trial.
In trial, the judge expects to have the latest will from Monica, spelling out her choice for custody.
The judge has set new terms for allowing the sisters to visit the children, allowing more visitation time, but no overnight stays.
He's also ordered all parties to turn over their passports. There was concern that the sisters might flee with the children to their native Brazil.