Thanks all.
In the end Forms 2.0 and the referrer (being the page containing/submitting the form) was a hairy point.
We ended up getting this to work in the following manner:
- Added form fields (to applicable (second page) forms) for Original Lead Source Partner & Last Lead Source Partner (forms 2.0)
- Added JS to form pages to parse parameters from referring landing page's (URL on our site) querystring
- Updated programs for these to check, using Filters, for the Last Lead Source Partner = [this campaign's value] in conjunction with having the proper Last Lead Source Content parameter
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