The link I have quoted tells you that if you WILL BE eligible to sponsor your partner for residence within the next year - that is, within the life of this partner-sponsored work visa that you want to apply for now - then you'll be eligible to sponsor her for the work visa. So since your other partner left somewhen around four years ago, even IF that visa counted like residence (which I don't think it does), from five years later, which must be fairly soon, you will be eligible to sponsor your new partner for residence, and therefore, a year before that, you'll be eligible to sponsor her for the work visa.