Fact Design and best practices

This is design question.

What if designing Order Line Items Fact.. However, not every order has line items.

Would you design Order Facts and Have line items as dimension?
or
Order Line Items Facts, but then what is the best practice to represent orders without line items?
or
would you create 2 separate facts which create another set of issues?

Thanks in advance.

What's an order without a line item? It sounds like the business in an inconsistent state.

I used order as an example. It is transactions, not every transaction has line items.

Thanks.

OK, got it. If one of the columns that defines the grain is optional, you can't build the fact at that level. In this case you would need two facts.