Based on the Procedures Advice Manual, a person should not be refused simply because they intend (whether this intention is stated or not) to apply a further visa. s65 delegates should not be seeking to block this pathway.
This question can rise with stated intention to apply visa (such as Partner visa) s65 delegates should focus on the assessing the genuine temporary stay in relation to the FA-600 visa which the person have applied not the relationship.
– The genuineness of relationship is part of a Partner visa application
– It is ok to apply FA 600 to maintain an established relationship
Visitor visa to student visa 500 or 485 Graduate visa (which is onshore application) are normal practice following this “intention to apply” principle.