Identity 2.0 - two contexts?

I used a bunch of code to create an Identity 2.0, MVC 5, EF6 application.
I started to add my non-Identity tables, some with FK to the Identity tables.
This is the context class for Identity:
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
Do I create a second context for the rest of my tables from dbcontext, or just use the ApplicationDbContext?
public partial class myContext : DbContext
I tried to delete ApplicationDbContext and just use one context that didn't inherit from IdentityDbContext, but ran into some errors.
So three ways to do it:
1) two contexts
2) use ApplicationDbContext inheriting from IdentityDbContext
3) use myContext (if I could figure it out!)