Invoice integration - BillingState/City in invoice function and createEstimate

Invoice integration - BillingState/City in invoice function and createEstimate

Is there any way to specify Billing State & City by invoice function ? I referred to the help page and found that I can specify "BillingAddress", but there weren't BillingState or BillingCity. Without these, we need to combine all the address values into "BillingAddress" but it will cause problems when we retrieve those data in templates etc.

Also, I want to create estimate in the same way to createinvoice(). Is there any function to create estimate such as createestimate()? If not, will it be supported in future ?