The parental controls are per-account (and has nothing to do with your ISP).
If you have individual accounts on each machine, then the parental accounts are, by extension, per machine.
If you have one server acting as a directory server, where all the accounts are created and the other machines authenticate against it, then setting the controls on the server will automatically propogate to the individual machines.
So the answer to your quesiton is: yes. It just depends on how you're setup.
Ok when you say "Account" do you mean Apple Account ?? So, since my childrens Apple devices are linked to my husbands account, are you saying that he could activate the parental controls on his account and this would then apply to each device connected to his account ?? Thanks and sorry if this is replying to you twice. Im just learning !
That would be the user account on the computer. Parental controls have no connection with an Apple ID or iTuens Store account.
There is no way to globally manage parental controls on all devices. Parental controls on the Mac are completely separate from controls on an iOS device. For a Mac, you set the parental controls for the user's account in Mac OS X (in the System Preferences) or, as Camelot indicated, on a Mac OS X Server, something few home users have or are willing to set up.
For an iOS device, you would set up the controls on each device individuall unless you want to obtain and learn a mobile device management system such as Apple Configurator, JAMF's Casper, or another such solution. For most home users it's easist just to set up the iOS devices separately.
No, I'm not referring to your AppleID account, but the individual users' accounts on the computer itself - I'm assuming that each of you, your husband and kids have their own username/password combinations to log into the machine... those are the accounts that I'm referring to, since the Parental Controls will apply to the specific username/password used to log into the machine.
If you don't have individual accounts setup then whatever controls you set will apply to everyone, including yourself.