Grokzen

# Based on post from: https://snipt.net/chrisdpratt/symmetrical-manytomany-filter-horizontal-in-django-admin/#L-26
# Only reposting to avoid loosing it.

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When adding a many-to-many (m2m) relationship in Django, you can use a nice filter-style multiple select widget to manage entries. However, Django only lets you edit the m2m relationship this way on the forward model. The only built-in method in Django to edit the reverse relationship in the admin is through an InlineModelAdmin.

Below is an example of how to create a filtered multiple select for the reverse relationship, so that editing entries is as easy as in the forward direction.

IMPORTANT: I have no idea for what exact versions of Django this will work for, is compatible with or was intended for.