Looked at code for dataverse again and noticed bits of code that seem to hook into existing forms and add plug-in specific elements

// Notify ArticleDAO of article metadata field (external data citation) in suppfile form
HookRegistry::register('articledao::getAdditionalFieldNames', array(&$this, 'articleMetadataFormFieldNames'));

// Metadata form: update cataloguing information. Prevent update if study locked.
HookRegistry::register('metadataform::execute', array(&$this, 'metadataFormExecute'));

Started adding code based on what those which should modify the issue data and create issue forms

//add hooks to issue objects to tell them about and deal with elements I'm adding HookRegistry::register('issuedao::getAdditionalFieldNames', array(&$this, 'issueFormFieldNames'));
HookRegistry::register('issueform::execute', array(&$this, 'issueFormExecute'));

function issueFormFieldNames($hookName, $args)
is simple and complete, not sure yet exactly what that does, but guessing it tells the form about the additional element so that whatever the form does to elements, it does to my element too.

function issueFormExecute($hookName, $args) {
is not complete, currently does nothing, but will eventually invoke a method in the OpenReviewDAO object that will update the openReviewIssuePref field with the current issue # and value from my dropdown.