Reply Templates and $RequesterName

Hello,
Are there any functions available that can be used on Content Variables (such as $RequesterName) to get only the first part of the variable. In our default reply template; we use at the beginning of the mail " Hi $RequesterName,"

Which translates to " Hi John Smith," (if John Smith was the requester)

Which is very formal. We are sending replies to people we know and work with all the time - I would like to just have the first name in the reply, rather than first and last name. Currently we just deleted their last name before we send it, but we sometimes forget.

In SQL, I would use the SUBSTRING function with CHARINDEX to find the first space in the string and return everything before it - like
SUBSTRING( $RequesterName, 1, CHARINDEX(' ', $RequesterName, 1)-1)

Are there any functions that can be used in ServiceDesk On Demand that would give me the ability to get the first name?
Or any fields I can add to my users list that I can input their first name.

I could use employee id for the user to store the first name, but employee id isn't available to me within content variables, so that doesn't help me.