Optional Model Validation in Razor Page

Question

I have a "create account" form where I would like to collect data related to more than one model. While this is easy to accomplish, I am not able to figure out how to make the validation optional in the case where I would like to make something optional. Consider the example below.

Pseudo Code Form

Create Account
  Account Name
  …
Create Primary Contact
  Contact Name
  Contact Email
Create Contact Address (Optional)
  [ ] Skip Address
  Address Type
  Street
  City, State zip

In this example, I would like the validation to run on "create account", "create primary contact," and on the "create contact address" if the "Skip Address" is not selected. Please note that each of the sections above has its own model and own database repository.