Unpermitted parameters: offices in a has_many :through association in Rails 5 - ruby-on-rails

Question

I have a has_many through association. When I go to the Store form I need to save Owner data in the same form. But I keep getting Unpermitted parameters: :offices. I tried with inverse_of as well. I tried changing the models structures like trying to accept attributes for all models.
Office Model:
class Office < ApplicationRecord
has_many :owner_offices, :dependent => :destroy
has_many :owners, through: :owner_offices
accepts_nested_attributes_for :owner_offices
#accepts_nested_attributes_for :offices
end
Owner Model:
class Owner < ApplicationRecord
has_many :owner_offices
has_many :offices, through: :owner_offices
accepts_nested_attributes_for :owner_offices
end
Owner_Office Model:
class OwnerOffice < ApplicationRecord
belongs_to :office
belongs_to :owner
accepts_nested_attributes_for :owner
end
Office Controller:
def new
#office = Office.new
#office.owners.build
end
def office_params
params.require(:office).permit(:office_name, :office_slug, :office_email, :phone, :office_type, :status, :mf_member, :comment,
:owners_attributes => [:office_id, :owner_id, :first_name, :last_name, :owner_email])
end
Office Form:
<%= form_with(model: office, local: true, html: {class: "form-office"}) do |form| %>
<div class="row">
<div class="col-md-6 col-sm-6 col-xs-12">
<div class="form-group">
<span><%= form.label :office_email %></span>
<%= form.text_field :office_email, class: 'form-control' %>
</div>
</div>
</div>
<hr>
<h3>Owner Information</h3>
<hr>
<%= form.fields_for :owners do |owner_form| %>
<div class="row">
<div class="col-md-6 col-sm-6 col-xs-12">
<div class="form-group">
<span><%= owner_form.label :first_name %></span>
<%= owner_form.text_field :first_name, class: 'form-control' %>
</div>
</div>
<div class="col-md-6 col-sm-6 col-xs-12">
<div class="form-group">
<span><%= owner_form.label :last_name %></span>
<%= owner_form.text_field :last_name, class: 'form-control' %>
</div>
</div>
</div>
<div class="row">
<div class="col-md-6 col-sm-6 col-xs-12">
<div class="form-group">
<span><%= owner_form.label :owner_email %></span>
<%= owner_form.text_field :username, class: 'form-control' %>
</div>
</div>
</div>
<% end %>
<% end %>
I just placed most of the part where I'm calling the fields_for for owner. So I'm stuck, not sure what I'm missing at the moment and I've been checking other resources as well, implementing a different logic.
Also, I do not want to use cocoon because is important to me to learn how to implement from scratch.
Thanks in advance.