Express form - Include multiple entity form in an entity form
I have an express form based on an entity 'Signatory' and another entity called 'Site' with his own form.
When the use is filling the Signatory form, he needs to be able to add one or up to 50 sites using the 'Site' form.
I tought I would be able to achieve this by using an association on the Signatory entity to have one to many sites.
But when I try to link the entity 'Site' in the 'Signatory' form using the associations it looks like it doesn't render the form, but he is looking for existing entities to link to the Signatory. It tells 'No available entries found.'
Is there a way to do what i try to do ? I mean displaying my Signatory form, and display a button 'Add sites' to add multiple new sites (not existing sites) without programmatically create a custom block?
Thank you in advance !