>     form
>      form_field_a
>      form_field_b
>      form_field_collection_tenant (with unlimited values) - add another item
>        field_collection_user_details (with unlimited values)  - add another item
>          field_u1
>          field_u2 etc
>        field_collection_instance_details (with unlimited values)  - add another item
>          field_i1
>          field_i2 etc