The closest example I can think is the TV show Party of Five.
In the US, there are very few cases of siblings raising siblings because of smaller family sizes. You almost never have parents dying with a 20 year old available to take care of a 5 year old; the more common case is parents dying and two or more siblings close in age go to foster care or another relative.
When the siblings are raising younger siblings, you have a high rate of poverty historically because it is as difficult as single motherhood but made worse by lack of experience. Because it is so difficult, this is why AIDS orphans with teenagers and younger children move in with grandparents - to have help, any help, from any involved adult.