How to prevent overwriting Ambiant-Mate theme (Upgrade to 20.04 LTS)

Hi!

I do not want that the upgrade process to Ubuntu Mate 20.04 LTS overwriting my modified "Ambiant-Mate".

How do I do that?

Just set the package "ubuntu-mate-themes" to hold in:
"/etc/apt/preferences.d"

with:
Package: ubuntu-mate-themes
Pin: release *
Pin-Priority: -1

is enough?

Or is enough to chattr +ai /usr/share/themes/Ambiant-MATE
to protect the folder and it's files inside to get overwritten?

I want also that the upgrade-process don't touch my .conf files
that I've edited in Ubuntu-Mate.

I found this solution to prevent the upgrade-process to
overwriting my edited .conf files of many things in Ubuntu-Mate.

Created file in "/etc/apt/apt.conf"

Added:

Dpkg::Options {
"--force-confdef";
"--force-confold";
}

How to prevent overwriting Ambiant-Mate theme (Upgrade to 20.04 LTS)?

Maybee copy /usr/share/themes/Ambiant-MATE to /home/user/.themes and completly remove the package "ubuntu-mate-themes"?