Custom Field: how to save array of multiple key-values in WordPress

Question

I have this kind of data on my database:

<wp:postmeta>

    <wp:meta_key>
        <![CDATA[property_icalendar_import_multi]]>
    </wp:meta_key>
    
    <wp:meta_value> <![CDATA[a:2:{i:0;a:2:{s:4:"feed";s:86:"https://www.example.com/ics-files/property.ics";s:4:"name";s:20:"IMPORT_1";}i:1;a:2:{s:4:"feed";s:56:"https://www.example.com/ical/property.ics";s:4:"name";s:16:"IMPORT_2";}}]]>
    </wp:meta_value>
    
</wp:postmeta>

As you can see, on meta_value I have two pairs of serialized data "name1/feed1" and "name2/feed2".

I wish to add, via custom fields, more instances to that array "name3/feed3)". But I don't know how to do it.

I was able to retrive the data so far:

    <?php
    $property_icalendar_import_multi = get_post_meta($edit_id, 'property_icalendar_import_multi', true);

    if(is_array($property_icalendar_import_multi)){
            foreach($property_icalendar_import_multi as $key=>$feed_data){
                print $feed_data['name'];
                print $feed_data['feed'];
            }

        }else{
            esc_html_e('nothing');
        }

    ?>

My question is now, how can I update (edit or add) this data with a metabox?

I know I have to use update_post_meta but I'm not sure how.

Can someone point me on the right direction?