[IDEA] Modify existing models to account for patches previously made during migration

[shi-jie-samuel-tan]

Is your feature request related to a problem? Please describe.
A lot of database default values were manually given during the Django makemigrations process previously. This could lead to unexpected model behavior.

Describe the solution you'd like
Take note of migration ambiguity errors in the next model update and make sure all the patch work are now explicitly described in the models.py