Marketo writing to Campaign Member Object

[Anonymous]

We have a fairly active channel partner marketing program. We're using URL parameters that write to a most recent lead source field in Salesforce to track the leads that come in through our channel marketing program. The problem with our structure is that the most recent leads source gets overwritten every time, so I lose the history each time we run a new campaign. I would like to see per campaign in Salesforce, which partners are directing prospects to our materials, be able to see data now with current campaigns, but also be able to refer back and report across all campaigns which partners are generating the most activity. 

I would like to write which partner referred the prospect to the campaign member object, but have been told that Marketo can't write to campaign member fields. 

Wondering if anyone has suggestions on how to get this done? 

Thanks!

[Josh_Hill13]

You can't write to Campaign Member, so you could setup triggers in SFDC to write to the object based on the most recent fields you have in Marketo.

You can alternately do this with the API back to SFDC.