To completely overwrite _module.less of Orange_Checkout module in a custom theme, the developer should place the file in the Custom/theme/Orange_Checkout/web/css/source directory. This will override the default _module.less file from the Orange_Checkout module and apply the custom styles to the theme. The Custom/theme/Orange_Checkout/frontend/web/css/_module.less and Custom/theme/web/css/source/Orange_Checkout/_module.less paths are not valid and will not work, as they do not follow the theme structure or the module naming convention. References: [Theme structure], [Module naming convention]

To move a block from one container to another, the developer needs to use the layout instruction with the element attribute specifying the name of the block and the destination attribute specifying the name of the container. The after attribute can be used to position the block relative to other blocks in the same container. The value “-” means that the block will be placed after all other blocks, i.e., as the last child. The value “last-child” is not valid for the after attribute and will not work. The element and destination attributes should use the names of the blocks and containers, not their aliases or classes. References: [Layout instructions], [Move an element]

To register a new page layout in a custom theme, the developer needs to create a layouts.xml file in the app/design/frontend///Magento_Theme/layout directory. The layouts.xml file should contain the element with the id, label, and file attributes. The id attribute is used to reference the layout in other layout files, the label attribute is used to display the layout name in the admin panel, and the file attribute is used to specify the path to the layout file relative to the web directory of the theme. The app/design/frontend///layouts.xml and app/design/frontend///Magento_Theme/layouts.xml files are not valid and will not work. References: [Create a new page layout], [layouts.xml]