Plugin to extend Gravity Forms : meta box

I need a small plugin to extend the functions of the Gravity Forms plugin. You con't have to change GF. At the forms-builder there is the possibility to create a form that will be inserted as a post, page or custom-post-type into wordpress. At this forms it's also possible to add custom-fields. For this type of forms i need a small extension : - when a custom-field is used i need an additional checkbox at the form-builder for this element where the user can select to use this custom-field into a metabox or not. - for all checked fields a new metabox at the wordpress-backend for the used post-type will be created. - this fields need the full field-functions as from the front-end - if a vialue is changed at the metabox, also the value into the GF form-data must be changed. General : - Everything must be work es an external plugin to GF. No Changes to GF. - Everything must be multilanguage ready with the wordpress language functions __ and _e - You need a running copy of the latest GF release. I don't give you access to the GF files.