I am using the entity reference module and flags to achieve a certain use case. Let me elaborate. In my site, there are nodes of type "TASK". They have a flag on them "Take Task". Now a logged in user can click the flag and he or she has undertaken the task. Now to show that he or she has completed that task, they upload a blog about it. There is a field in the blog "TASK NAME" which is a entity reference field linking to the different nodes of type TASK. The user can select a task from the drop down so that it can be indicated which task has the user completed and blogging about and then in the blog they can upload details about it. Now i want that in that drop down provided by the entity reference only those nodes which have been flagged by the user appear. How can i achieve this?