One of my customers has an SFDC custom object, Student Programme, with more than one lookup to the Contact object, i.e. a Booker and a Student. Marketo appears to be automatically selecting the first one (the Booker) in the list, but we want the Student to be the relationship field. Does anyone know how this might be achieved? Marketo support are telling them that it has to be changed in SFDC, but they are not telling them what needs to be changed, so their SFDC admins don't know what to do. Current status is that we've removed the custom object from syncing at the Marketo admin end (removing the green tick) so that we can make any changes and then re-enable it, but unless we know what to change, I expect we will be in the same position as before. Would appreciate any advice. We need both lookup fields, but want to choose the field for the relationship.
It's really difficult to assist without being able to see the instance... I assume you are using SFDC Contact record types to define Student versus Booker?
Is there any chance you have a junction object between Contact and Student Programme to manage a one to many or many to many relationship going on? Can you give us a bit more details on your object setup?
Would you be willing to show a screenshot of your custom object list as it appears in Marketo to help with troubleshooting?