JomSocial doesn't actually have a unique name field as it shares the name from the core Joomla user. That is just one name, not separated first and last. but it should be split automatically into the default "firstname" and "lastname" fields in DT Register.
Nathan is no longer affiliated with DTH since the recent acquisition. You can connect with him and get any type of Joomla website help at
www.JoomlaEmployee.com
.