Django: How to organize migration for two related models and automatically set default field value for id of newly created object?

Suppose there is a production database, there is some data in it. I need to migrate in the next tricky case.

There is a model (already in db), say Model, it has foreign keys to other models.

class ModelA: ...
class ModelX: ...

class Model:
  a = models.ForeignKey(ModelA, default = A)
  x = models.ForeignKey(ModelX, default = X)

And we need to create one more model ModelY to which Model should refer. And when creating a Model, an object should have some default value related to some ModelY object, which is obviously not yet available, but we should create it during migration.

class ModelY: ...
class Model:
  y = models.ForeignKey (ModelY, default = ??????)

So the migration sequence should be:

• Create ModelY table
• Create a default object in this table, put its id somewhere
• Create a new field y in the Model table, with the default value taken from the previous paragraph

And I'd like to automate all of this, of course. So to avoid necessity to apply one migration by hands, then create some object, then write down it's id and then use this id as default value for new field, and only then apply another migration with this new field.

And I'd also like to do it all in one step, so define both ModelY and a new field y in the old model, generate migration, fix it somehow, and then apply at once and make it work.

Are there any best practices for such case? In particular, where to store this newly created object's id? Some dedicated table in same db?

from Django: How to organize migration for two related models and automatically set default field value for id of newly created object?