If I have booked an all-inclusive hotel does that mean that I can use...

If I have booked an all-inclusive hotel does that mean that I can use the facilities and eat in the restaurants of other properties within the same hotel chain or brand, in the area or country that I'm staying in?

This is not usually the case. If there are inter-dining options available between hotels then this is always clearly stated in a tour operator's/supplier's brochure or on their website. In all other cases please assume that you are only a resident of the hotel that you are staying in and the facilities available and restaurants that you can eat/drink in are only the ones in the hotel in which you are booked in to and staying in. If you wish to visit another hotel, for a day, perhaps as a guest of another wedding then a day pass rate will usually be charged for an all-inclusive property, and any food or drink consumed for a drinks reception, or dinner reception will be charged at the usual 'non-resident' rate as you are not a resident of that particular hotel.