How to preselect and disable specific checkboxes using js jquery

Question

I have checkboxes with randomly generated ids on every page view and want to preselect and disable some of them, so they can not get unchecked anymore. Is it possible?

With a simple script which looks after value="" I'm able to achieve the preselection but if I try to disable it at the same time, it disables all input fields on the page.

On closer inspection I found out that they have these attributes in common: <div id="cb-selection">and <input name="mycb">.

What would be your solution if we had this:

<form method="post" id="submit-this" class="" enctype="multipart/form-data">
    <div id="cb-selection">
        <div>
            <input type="checkbox" name="mycb" id="?" value="Check1">
            <label for="?"> Check1 </label>
        </div>
        <div>
            <input type="checkbox" name="mycb" id="?" value="Check2">
            <label for="?"> Check2 </label>
        </div>
        <div>
            <input type="checkbox" name="mycb" id="?" value="Check3">
            <label for="?"> Check3 </label>
        </div>
    </div>
</form>

I would appreciate any help.