In Linked I greet my contacts with a formal salutation and the family name. So actually I have to use the fullname and after inserting I cancel the first name. It would be great to have a simple family name feature. (Str$fullname - Str$firstname) would be cool. In rare cases of degrees and titles of course, I have stil to edit. What do you think? - Thanks for supporting this idea! 
You can do that by using our split function on the full name and take the second element like this
{=split({linkedin-name}, " ")[2]}