Customizing assign shipment template in Frontend Dashboard is possible through action hooks

Note: This is introduce in Frontend Manager Add on version 5.2.4 and up.

The following snippets on how to remove specific field in assign shipment template

    // Remove Assign Client field
    remove_action( 'wpcfe_assign_form_content', 'wpcfe_assign_client_callback', 10, 1 );
    remove_action( 'wpcfe_bulk_assign_form_content', 'wpcfe_assign_client_callback', 10, 1 );

    // Remove Assign Agent field
    remove_action( 'wpcfe_assign_form_content', 'wpcfe_assign_agent_callback', 10, 1 );
    remove_action( 'wpcfe_bulk_assign_form_content', 'wpcfe_assign_agent_callback', 10, 1 );

    // Remove Assign Employee field
    remove_action( 'wpcfe_assign_form_content', 'wpcfe_assign_employee_callback', 10, 1 );
    remove_action( 'wpcfe_bulk_assign_form_content', 'wpcfe_assign_employee_callback', 10, 1 );

    // Remove Assign Branch Manager
    remove_action( 'wpcfe_after_designation_dropdown', 'assign_branch_manager_dropdown' );

    // Remove Asign Company Branch
    remove_action( 'before_wpcfe_shipment_form_submit', 'wpcbm_assigned_branch', 10, 2 );

The following snippets on how to add additional fields in assign shipment template

    // Add Custom field to the template
    // Note: In this sample code the metakey is - my_custom_meta
    function my_custom_field_callback( $shipment_id ){
    ?>
       <div class="form-group">
   <label for="my_custom_meta" class="active">Custom Field</label>
         <input class="form-control" type="text" name="my_custom_meta" value="<?php echo get_post_meta( $shipment_id, 'my_custom_meta', true); ?>" placeholder="My Custom Field">                 
       </div>
       <?php
    }
    add_action( 'wpcfe_assign_form_content', 'my_custom_field_callback', 10, 1);
    add_action( 'wpcfe_bulk_assign_form_content', 'my_custom_field_callback', 10, 1);
    // Save the custom metakey data
    function save_my_custom_field_callback( $shipment_id, $data ){
        // Check id my_custom_meta is submitted
  if( isset( $data['my_custom_meta'] ) ){
           // save my_custom_meta value
     update_post_meta( $shipment_id, 'my_custom_meta', sanitize_text_field( $data['my_custom_meta'] ) );
  }
    }
    add_action( 'wpcfe_assigned_shipment_save', 'save_my_custom_field_callback', 10, 2 );

OUTPUT: