Per the Royal Mayan occupancy policy:
...The Maximum number of occupants generally allowed to utilize a villa is six; four in the master suite and two in the adjoining lock-off bedroom and bath. However, one additional occupant shall be permitted in the master suite, thereby increasing the total number of occupants for the master suite to five and for the entire villa to seven, subject to the following rules: (i) advance notice is required and (ii) if none of the five intended occupants of the master suite is younger than sixteen years of age, a special daily usage fee for the additional occupant must be paid in advance.
Whether this policy is the same for the Sands, I don't know. Based on my stays at the Sands, the rules are rarely or lightly enforced, if enforced at all.