Take the last letter of the first name, and use that as the first letter of your new name. Take the second letter of the last name, and make sure that letter is in the name somewhere.
Example:
Joan - Nicholas - Shiloh - Hannah
Joan ends in "N" and the second letter is "O"
Nicholas starts with "N", contains an "O" - ends in "S" with a second letter of "I"
Shiloh starts with "S", contains an "I" - ends in "H" with a second letter of "H"
Hannah starts with "H" and contains a second "H"
Ready, set, go!
Suzanna