Depends on the child. 2 double bed is enough for 4 adults, and if the child stays in a crib (which is usually available for free), then it will be totally fine.
However, if the kid needs a bed, then it will be 2adults+1kid on a double bed, then it will be a little bit tough.
However, if the kid needs a bed, then it will be 2adults+1kid on a double bed, then it will be a little bit tough.