How to install demo content manually?

@designdiverso, feel free to contact https://trilby.media for your migration needs.

@rhukster

hi, do you work there?

Yes

@rhusker

are you Andy? just wondering what do you think of my inquiry I just sent via the form on
your website

@designdiverso I think Andy (@rhukster) will already help you out. For your question concerning updates. The best is to create your own theme and use theme inheritance ( https://getgrav.org/blog/theme-development-with-inheritance ). In this way you keep your changes even the base theme gets updated.