I have one model, that I use to show and edit my values/fields and two or more models that are generated always with identical fields through other modules.

This sub-models containing different transaction engines. I want to integrate the fields of the sub-models into my main model depending on a field that contains the sub-model name. The clue is that some of my fields in the main model should than point to the corresponding fields in the sub-models. 

I tried different things as switching the environment, inheritance or using referenced fields. But nothing seems to work in a way that is useful. 

Any ideas how to get this to work.?

For a better understanding I place here some code of my trial with fields.Reference:

class ExchangeProvider(models.Model):
    ref_provider = fields.Reference(
        [('exchange.provider.internal', 'Internal'), ('exchange.provider.dumy', 'Dumy')],
        'Accounts PR')
    balance = fields.Float(
       'Balance Pr', related='ref_provider.balance') # NOT WORKING!!!

With the field ref_provider I declare witch transaction engine (Account) I will use. The Balance field should then show the Balance of this Account. But this creates an error because it is not a normal relation. I could try to get out the model and the id separat from re_provider and then merge it together for the related field.