I have never found any great way. I currently just change the name on the demographics and put the maiden name in parentheses. Another option would be to change the name and then enter a new pt. chart with the old name and just put in the chart the name change so you would know where to look.
Unfortunately in this day and age you might have several generations - married, divorce, maiden, remarried, divorced, etc.
In my old paper charts they would just change the name on the chart and maybe put a parentheses with the maiden name.