When setting up item 112 you will notice in the MBS that the fees are derived based on the consultation item associated with it.
Therefore the best way to setup item 112 in Medilink is to have multiple versions of it with a description for each of the other main consultation items.
You can see the ready reckoner for item 112 below here:
http://www9.health.gov.au/mbs/ready_reckoner.cfm?item_num=112
So for example if we set up a 112 for item 110 and item 116:
We then get a warning about it being a duplicate, that is OK and we want to click YES to add it too.
(Note, if required you would need to add description versions for 119, 132, 133, etc.)
Then when we are billing we add the consult item first, then add the 112 item and use the Next button to cycle to the appropriate version of it (the one that matches the consult item we billed):