Hi @Des44
When you clone a template from the default system template folder, the clone gets “detached” from that folder and placed outside of it. This causes all the references to the other templates become incorrect, as the clone is no longer in the system folder.
In order to address this, you can use one of the following options:
(1) Clone all the referenced templates as well, placing them all in a similar folder structure
(2) Update the references in the cloned file to have the full path to that template (instead of relative path)
For example, this piece in your cloned template:
{% extends "../membership-base.html" %}
would need to become something like this (pointing to the system folder):
{% extends "@hubspot/cmsdefaultsystempages/templates/membership-base.html" %}
Hope this helps!