Change position of fields at runtime.

BH
Hi, I have a report which has fields like "First Name" and Last name".  The values vary so sometimes the "First Name" field is wide and sometimes its narrow.  I would like the last name to follow immediately after the first name, regardless of how large the "First Name" field is.  I've attached the screenshot of desired behavior.   How do i accomplish this?
Thanks so much for your help.

Aron