Its a good thing in this country we don't separate children from their parents when their parents are in jail on remand.You are quite at liberty to detain illegal immigrants if that is what the law of your country says. However, until they are found guilty in a court of law, it's my understanding that they are not guilty of any offence in your country and thus there is no valid reason to separate them from their children. Unless the rule of law doesn't apply in your country - could you confirm whether it does or not please?
If they are found guilty of an offence, then if the law of your country says "Deport", then by all means deport them, With their children at their side.
I'm not sure how difficult that is to understand for someone living in an allegedly democratic country.
You going to start whining about the rule of law in the UK?