{% load bootstrap4 %}
<div class="row">
    {% bootstrap_field form.title form_group_class='col-md-3 form-group' %}
</div>
<div class="row">
    {% bootstrap_field form.first_name form_group_class='col-md-6 form-group' %}
    {% bootstrap_field form.last_name form_group_class='col-md-6 form-group' %}
</div>
<div class="row">
    {% bootstrap_field form.line1 form_group_class='col-md-8 form-group' %}
    {% bootstrap_field form.line2 form_group_class='col-md-8 form-group' %}
</div>
<div class="row">
    {% bootstrap_field form.line4 form_group_class='col-md-4 form-group' %}
    {% bootstrap_field form.state form_group_class='col-md-4 form-group' %}
    {% bootstrap_field form.country form_group_class='col-md-4 form-group' %}
</div>
<div class="row">
    {% bootstrap_field form.postcode form_group_class='col-md-4 form-group' %}
    {% bootstrap_field form.phone_number form_group_class='col-md-4 form-group' %}
</div>