I agree with your first option, autofill to 1, 2, 3, etc. and let us change it if we'd like. Otherwise, the second option you list is the next best idea.
Servicio de atención al cliente por UserEcho
I agree with your first option, autofill to 1, 2, 3, etc. and let us change it if we'd like. Otherwise, the second option you list is the next best idea.