adding a person into a pic

hello,
i have a pic with 4 of my aunts in it, and one of my aunts was left out, and she want to be in it with her sisters. my question is what is the best way to take a pic of someone and place it into another pic and make it look as natural as possible??

thank you

 

check this out http://www.jasc.com/support/learn/?
try to get this program. you could do whatever you want to a picture. check out the tutorials

 

go here
http://www.jasc.com/support/learn/tutorials/archive/paintshoppro/clone1.asp?pg=1

 

thank you, i think this will help