Hi Brajesh,

thank you so much, this works just perfectly!! You’re amazing! I will keep in mind it could get resource heavy and change the setup in case my user base would grow a lot, but for now I don’t rly have that many users so it should be okay for some time. I really really appreciate you taking your time to create a solution for me.
I’m now trying to work on the nested conditions (as i mentioned before in my first post) and i came up with something like this:

 function bp_friends_suggestions_pro_get_xprofile_query($suggestion_rule_id) {
    if (!is_user_logged_in() || !$suggestion_rule_id || empty(get_post_meta($suggestion_rule_id, '_is_active', true))) {
        return array();
    }

    if (!bp_is_active('xprofile')) {
        return array();
    }

    $user_id = bp_loggedin_user_id();
    $matching_rules = (array) get_post_meta($suggestion_rule_id, '_matching_rules', true);
    
    // New meta field for rule grouping
    $rule_groups = (array) get_post_meta($suggestion_rule_id, '_rule_groups', true);
    
    if (empty($matching_rules)) {
        return array();
    }

    $xp_query = array();
    $mandatory_rules = array();
    $optional_rules = array();

    // Split rules into mandatory and optional based on group settings
    foreach ($matching_rules as $index => $rule) {
        if (empty($rule['field_id']) || empty($rule['match_field_id']) || empty($rule['operator'])) {
            continue;
        }

        $value = maybe_unserialize(BP_XProfile_ProfileData::get_value_byid($rule['field_id'], $user_id));
        
        // Determine comparison operator
        switch ($rule['operator']) {
            case '=':
            case '!=':
            case 'LIKE':
            case 'NOT LIKE':
                $compare = $rule['operator'];
                break;
            case '<':
                $compare = '>'; // opposite
                break;
            case '<=':
                $compare = '>=';
                break;
            case '>':
                $compare = '<';
                break;
            case '>=':
                $compare = '<=';
                break;
            default:
                $compare = null;
                break;
        }

        if (!$compare) {
            continue;
        }

        // Handle array values
        if (is_array($value) && !in_array($compare, array('IN', 'NOT IN'))) {
            if (count($value) === 1 && !bp_friends_suggestions_pro_is_multi_valued_field($rule['match_field_id'])) {
                $value = array_pop($value);
            } else {
                $value = maybe_serialize($value);
            }
        }

        $query_item = array(
            'field' => $rule['match_field_id'],
            'value' => $value,
            'compare' => $compare
        );

        // Special handling for field_id 43
        if ($rule['field_id'] == '43') {
            $queries = bpfscustom_get_multiselect_field_query(
                $user_id, 
                $rule['field_id'], 
                $rule['match_field_id'], 
                $compare
            );
            if (!empty($queries)) {
                if (isset($rule_groups[$index]) && $rule_groups[$index] === 'mandatory') {
                    $mandatory_rules = array_merge($mandatory_rules, $queries);
                } else {
                    $optional_rules = array_merge($optional_rules, $queries);
                }
            }
            continue;
        }

        // Add to appropriate group based on rule_groups setting
        if (isset($rule_groups[$index]) && $rule_groups[$index] === 'mandatory') {
            $mandatory_rules[] = $query_item;
        } else {
            $optional_rules[] = $query_item;
        }
    }

    // Build nested query structure
    if (!empty($mandatory_rules)) {
        $xp_query[] = array(
            'relation' => 'AND',
            'rules' => $mandatory_rules
        );
    }

    if (!empty($optional_rules)) {
        $xp_query[] = array(
            'relation' => 'OR',
            'rules' => $optional_rules
        );
    }

    if (!empty($xp_query)) {
        $xp_query['relation'] = 'AND';
    }

    return $xp_query;
} 

and then this:

// Example of how to store rule groups
$rule_groups = array(
    0 => 'mandatory', // First rule is mandatory
    1 => 'mandatory', // Second rule is mandatory
    2 => 'optional',  // Third rule is optional
    3 => 'optional',  // Fourth rule is optional
    4 => 'optional'   // Fifth rule is optional
);
update_post_meta($suggestion_rule_id, '_rule_groups', $rule_groups); 

Could you please just tell me what you think of this approach? I originally wanted to incorporate the ability to choose whether the condition is mandatory or optional into the form, but I just couldn’t rly manage. I would love any form of feedback from you, but it’s totally okay if you don’t have a time/space for it, as im already extremely grateful for your help regarding the multi select.

Best regards
Alex