Brother invited a friend with a couple to have group sex like real swingers

When half-brother and sister visit a similar couple, then all four plan to have fun with each other from the word to the fullest. But the cunning lads make a knights move and, putting on masks, change girls. Those who do not suspect the catch at first, and when they end up a couple of times, then its already quite late to change. Well, if all four wanted entertainment, they get it!