I wanna use the official hr module, But I wanna use my own fields. So I need to change the type of many fields.

eg. In the hr.employee, I wanna change the field:address_home_id from type "many2one" to "char". How can I do it ?

I know two ways:

First: settings->custom->model->edit.. It seems that I change it correctly, But it is not changed in the view.

Second: go to the source of the module;change the code:

'address_home_id': fields.many2one('res.partner.address', 'Home Address'),

to

'address_home_id': fields.char('Home Address',size=32),

But when I create a new record, failed!

Can somebody tell me how to get it right?

Thank you in advance!