Execute code before sending the order to 2Checkout. This hook passes the user ID of the order’s customer and the MemberOrder object.

do_action( 'pmpro_before_send_to_twocheckout', int $user_id, MemberOrder $morder );

Parameters

$user_id

int

$morder

MemberOrder

Source

File: https://github.com/strangerstudios/paid-memberships-pro/blob/master/preheaders/checkout.php