Register a Posts2posts connection via a Gravity Form

I've created a Gravity form for users to submit associated resources to a training module. This is done through CPTs for 'Associated Resources' and 'Training Modules'. The 'Gravity Forms + Custom Posts Types' plugin manages the form posting to the CPT and it does it brilliantly.

The Associated Resources are associated through the Posts2Posts plugin. This puts a new box in the editing screen of the two custom post types to select the posts you want to associate with them. At the moment, a logged in user can make this association when editing the Training Module or Resources posts (great!) but they can't make this association when uploading a new resource on the front end through the Gravity form (not so great).

The user is able to input the Resource title, URL and type of file into the Gravity form and push the data to a new 'Resource' post, but I can't figure out how the form can also register the Posts2Posts association.

Any help? Please?