So i've tried to book my flights with JQ on the EK website however there were website issues and the booking couldn't be made.

Contacted EK by email and they informed me that they are not able to price an EK fare with a JQ connection. However they can do so on Virgin from LST...

Bit odd... why list the JQ and QF connections in the booking engine if these can't be priced or booked?

For personal reasons we do not wish to travel on Virgin and are therefore looking for either a JQ, or preferably QF, connection.

If the single flight booking LST-MEL-AMS and return can not be made using either JQ or QF connecting flights I am planning to make two separate bookings... however then utilising QF out of Devonport for the flights to and from MEL and EK for the onward flight to AMS - since this will give me QF flights for both outbound and inbound journeys and avoids JQ.