Is it possible to have a child of a child theme in Magento 2

Question

I have a theme installed using Magento 2 and I then have a child theme which I am using to make customisations.

Is it also possible to then create a child them of that child which I can use to make a custom header design which will take everything else from the child theme.

I essentially only need to replace the header logo on some pages like the home page and a child > child theme seems like an easy solution but not sure how to make it work.

Answer 1

Yes, You can create child theme of child theme. You have to defined old child as parent in new child theme

new child theme.xml

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
    <title>New Child Theme</title>
    <parent>OldChildtheme/customthem</parent>
    <media>
        <preview_image>media/preview.png</preview_image>
    </media>
</theme>

Answer 2

I think you just need to create a child theme inside your current child theme and specify your current child theme as the parent of your new child-child-theme. That will do the trick.

So your child-child theme theme.xml should look like:

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
    <title>Child Child Theme</title> 
    <parent>Currentchild/themename</parent> 
    <media>
        <preview_image>media/preview.jpg</preview_image> 
    </media>
</theme>

Magento uses infinite callback mechanism for the themes. That means you can have infinite number of children under a theme and Magento will pick the right file from the parent if it didn't find one from the relevant child.