Most private places are managed by a company. That company will refer you to people who are allowed to access the property. Likely they will not allow a "stranger" to access the property at all. So, the first place to check is with the property manager.
As was said above, if they are staying in a resort, they will most likely receive daily maid service (depending upon which resort they are staying). As for a "cook", that's what restaurants are for, LOL. Although there may be exceptions, very few resorts will allow a stranger to enter the premises for the purpose of cooking for guests in their rented hotel rooms. Plus, the vast majority of hotel (resort) rooms won't have a full kitchen anyway -- most won't have an oven, and some won't have all of the necessary cooking implements. Anyway, coordinating a private cook for a family staying at a resort will be very difficult, but not impossible.