Scenario

You are sending traffic to funnel A (to the traffic node).

You decide to make funnel B and want all funnel A traffic to jump to funnel B instead.

Solution

Connect the traffic node in funnel A to a PHP node, and have that PHP node route the traffic to funnel B.

Here is the code you should put in the PHP node:

<?php

require_once 'PHPNodeHelpers.php';

$trackingFields = PHPNodeHelpers::loadTrackingFields();
$currentTrafficSourceId = '{trafficsource-id}';
$targetFunnelId = '[[target-funnel-id]]';

$queryParams = $trackingFields;
$queryParams['flux_fts'] = Crypter::fastEncodeDigits( [$targetFunnelId, $currentTrafficSourceId] );
$url = 'http://{flux-domain}?'.http_build_query($queryParams);
Permalinks::fastRedirect( $url );

?>

Then, open the advanced settings of funnel A and you will need to define the ID of funnel B that it will be sending traffic to.

You could also define it in the above code directly, but we like to declare this as a custom token so that the above code is reusable.

Solution 2 - if you want to send to a specific node ID

Connect the traffic node in funnel A to a PHP node in the same way.

Use this code in the PHP node instead:

<?php

require_once 'PHPNodeHelpers.php';

$trackingFields = PHPNodeHelpers::loadTrackingFields();
$currentTrafficSourceId = '{trafficsource-id}';
$targetFunnelId = '[[target-funnel-id]]'; //can also change this here
$targetNodeId = '[[target-node-id]]'; //can also change this here

$queryParams = $trackingFields;
$queryParams['flux_fts'] = Crypter::fastEncodeDigits( [$targetFunnelId, $currentTrafficSourceId] );
$queryParams['flux_fn'] = $targetNodeId;

$url = 'http://{flux-domain}?'.http_build_query($queryParams);
Permalinks::fastRedirect( $url );

?>

Here you can declare the flux_fn globally in the advanced settings > custom tokens box, like with funnel ID.

However, if you need these nodes to be specific or have multiple nodes in a funnel, you can simply write the funnel ID and node ID in the PHP code directly, e.g.

<?php

require_once 'PHPNodeHelpers.php';

$trackingFields = PHPNodeHelpers::loadTrackingFields();
$currentTrafficSourceId = '{trafficsource-id}';
$targetFunnelId = 'xxxxxxxxxxxx'; //can also change this here
$targetNodeId = 'xxxxxxxxxxxx'; //can also change this here

$queryParams = $trackingFields;
$queryParams['flux_fts'] = Crypter::fastEncodeDigits( [$targetFunnelId, $currentTrafficSourceId] );
$queryParams['flux_fn'] = $targetNodeId;

$url = 'http://{flux-domain}?'.http_build_query($queryParams);
Permalinks::fastRedirect( $url );

?>