Getting multiple models bound to a form that uses a modal in Laravel 5.1

I'm trying to add a modal popup that allows a user to save a "featured image" with their article. I'm getting tripped up combining the two models in the form, and getting it to save the relationship properly. I have my controllers, models, and blade files here:

http://ift.tt/1NTjDEL

Any pointers in the right direction would be much appreciated. Thanks in advance!

via Chebli Mohamed