to whom it may concern:
i am writing this letter to invite our/my parents (name and brith days) to visit us in australia this coming may for a period of () months.
it goes without saying that we will cover all expenses during their visit in australia, which includes international air tickets, local transportation, accmodations, medical insurances and all other related expenses.
your favourable consideration regarding their visa applications will be highly appreciated. if you have any question regarding this matter, please kindly contact me/us at the address above.