Did you plan to work on a Drupal 8 version ?
I will need to implement such a feature for a Drupal 8 project during summer, i could work on it if you don't mind.
I'm not totally aware about the limitation in number of columns for a field storage, but i have good expectation that if it can work with a basic entityreference field, i will also work with inline_entity_form and even with paragraphs.
Did you plan to work on a Drupal 8 version ? I will need to implement such a feature for a Drupal 8 project during summer, i could work on it if you don't mind. I'm not totally aware about the limitation in number of columns for a field storage, but i have good expectation that if it can work with a basic entityreference field, i will also work with inline_entity_form and even with paragraphs.