websauna populate table with data from users

Question

I'm just starting digging into websauna and python frameworks, and have one question. How can I create a table that will be populating based on websauna.system.user?

For example table 'example' should contain two columns:

1. user_id based on users.id
2. some_float with default value 0.0

And when new user will be added this "example" table will automatically populated with new row "some_user_id_from_users.id | 0.0"

As I understand this populate can be done by sqlalchemy.backrefs, but I'm not really clear on how this can be implemented from the documentation because it looks like that "User" class should populate this "example" table. Or, maybe, I should proceed with modification of user creation process?

Any advise or example will be greatly appreciated

PS sorry for my English)