Replace background — Add exotic background in holiday photographs

"This is a photo of my sister and her family holidaying in Italy. Afterwards they went to Cambodia, of which they most enjoyed their visit to the Bayon temple in Siem Reap — I believe the smiling faces on the huge towers around the temple are just awesome! But well, they just forgot to take a picture there... Would you place the three of them in this 'smiling monument' photo please... A surprise gift for my sister!"