So one day I'll figure it out - who are the adults here? Nancy clearly lived with them for a while, but neither is Fritzi and I haven't been able to find info on who they are.
ChatGPT to the rescue:
"The Sputters are a recurring family in the Nancy comic strip, created by Ernie Bushmiller. They first appeared in Comics on Parade #5, published in 1937. 
The Sputters serve as comedic foils to Nancy and her friends, often depicted as neighbors with a chaotic lifestyle. Their exaggerated, disheveled behavior contrasts with Nancy’s more grounded perspective, adding humor to the strip."
Notably, Mr. and Mrs. Sputter bear a resemblance to Dagwood and Blondie Bumstead from the Blondie comic strip, suggesting that Bushmiller may have drawn inspiration from these characters."
Over time, the Sputters’ characters were developed to highlight the humorous disparities between their disorderly household and Nancy’s more orderly environment. This dynamic provided a rich source of situational comedy, enhancing the strip’s appeal."
Comments
"The Sputters are a recurring family in the Nancy comic strip, created by Ernie Bushmiller. They first appeared in Comics on Parade #5, published in 1937. 
Nancy is a pretty subversive comic strip!