Retail ePOS - Initialize RetailTransaction by Code

I need to create a BlankOperation to add a Customer to the sale, I'm using the AddCustomerToTransaction(customer, posTransaction) method, it works just fine when there is at least one item added to the sale but if there are no items the BlankOperation does nothing, if I check my RetailTransaction retailTransaction = posTransaction as RetailTransaction is blank.

Is there a way to initialize the retailTransaction when there are no items?

If I add the customer through the SearchForm even when there are no items on the sale, the Customer is added and the retailTransaction seems to be initialized, I was looking at the code within the frmCustomerSearch and Customer.cs but can't find how that initialization happens.

Thanks in advance.