I think you are right. The form verbs take to express a hypothetical or possible situation.
I don't know a lot but I just did a class about this.
But to change perfect past tense completed in the past by changing the verb is or could be by replacing the verb with the action to was ,did ,before, ect. I think this might help
The most appropriate synonym for the word children would be "Youngster"
Hope this helps!