[Answer]-Django smart/chained select manytomanyfield

What you describe is a misuse of the ManyToMany relation.
If you want to create a many-to-many relation between A and B, all you have to do is add a ManyToMany field in the definion of one of the models (A or B) and django will take care of the rest. Specifically, it will create a 3rd table where it will store the associations in the form of (A.id, B.id). This is standard rational database procedure for this type of relations, and Django is implementing it.

See http://en.wikipedia.org/wiki/Junction_table for the general definition of a many to many relation.

https://docs.djangoproject.com/en/1.5/ref/models/fields/#manytomanyfield – for the Django implementation.