Paint shop pro or photoshop elements will allow you to select cut and paste different elements of your photo`s into one pic, and make it look as if two people were together.

There are some freeware photo editing programmes but I dont know if they would enable you to do this easily or at all.

I use photoshop CS3 which is perfect for the job, but it`s a very expensive programme, and only worth the expense if you`re going to do a lot of photo editing.