if they grow up here, it IS their country, to them
The reasoning you are using is unrealistic.
Change the application and we both know that type of reasoning can't work.
My family comes for a visit in your house. We live there for a period of time. One day you come home and find we have changed your house around and have thrown out your music collection.
To us, we are living there so its our house.
there should be a way for them to gain 'legal' status without deportation
There is.
Legal immigrants do it all the time.
Once they are adults, and they did not break the law that a child cannot break
Did you actually read what you wrote?
The fact that they are adults means the laws they break is because they are adults. They are no longer children. The child grace period has expired, no longer applies.
Most people, including aged teens, are not oblivious to the things that matter in life. Mostly.
If you are 16 or 17 you are going to question your legal status.
You're going to find out what it takes for you to be a citizen when you do reach suffrage. You're going to ask your legally immigrated parents or guardians about it. Its not going to be a birthday surprise.
We're not talking 8 year olds, we're talking high school graduate age. Simple reasoning and deduction is usually not a mystery.
Those are not the people with problems.
The people with problems are the ones that think they can ignore it and it will go away. Or they believe they have some kind of special power that allows them to break those laws unpunished.
When they get caught, they get deported.
As they should be.
One is honest, responsible and reasonable.
The other is dishonest deceit.