Registrants are unable to transfer a registration without admin assistance. Note that the substitute must be eligible for the original ticket. In other words, a non-member may not register under a member ticket, even in a substitution scenario.
Go to Orders and Transactions > Order Manager and use the Search to find the original order. Click on the order number.
Scroll to the Order Details section, about halfway down. Click on the appropriate ticket.
Update the registrant. When editing a member ticket, a drop list allows selection of the replacement member. When editing a guest ticket, text boxes hold the new guest's information. Select or enter the new information, then click Save.
Substituting a member registration is only possible if members are allowed to register one another. If the drop-list doesn't appear, this is the reason why. To allow members to register one another, go to Meetings > Settings > Permissions and clear the box marked Prevent Members From Purchasing Tickets For Other Members. Save these changes, then re-try the steps in this article. Once members are allowed to register one another, member substitions become possible.
Tip: Substitution only works when using the same ticket for the new registrant. If the purchaser ordered the wrong type of ticket, use the Cancel and Replace option instead.