Question
The S1E1 intro to The Umbrella Academy clearly states that 43 children were born on that day as "immaculate conceptions"(or however you want to define it).
Hargreaves gets 7, but we never hear what happened to the other 36.
Did he try and purchase them and was rebuffed?
Did he know they were not "special" and not bother?
On a related note; are Hazel and Cha-Cha from the 36? They seem to be able to survive incidents that would kill a regular human.
Answer
The Show didn't elaborate it much and also show is not finished yet but source material did elaborate a bit:
Below is the graphic image of one kid's birth with the text "...the ones who survived" (suggesting some died too):
Also in from another panel:
This shows that Hargreaves tried to adopt as many as he can but he got only seven.
So there is a possibility that rest also died or never developed power or say hidden.
Also from Heavy.com:
TV Guide asked Steve Blackman, the showrunner, and Gerard Way, the author of the comic, about those other children. They simply said this was a good question that they couldn’t answer.
Answered By - Ankit Sharma