How to implement custom Checkboxes in Checkout
Check out one of the following modules:


Commerce Checkout Field Group:


  Commerce Checkout Field Group turns Commerce order field groups into checkout panes.
  This allows to add custom fields to the checkout pages.

Commerce Fieldgroup Panes:


  This module creates for each field group of the order entity a new checkout pane. These panes can be activated or deactivated as usual.
  This enables an easy way to collect information in the checkout process. For example customer comments, feedback about where the customer founds the shop or any other fieldable information.