If your contracts have separate master contract numbers, you can only use points from a single contract for a single night. Unless you use your once a year transfer to transfer from one contract to another.
You can tell the difference in the types of contracts by the number of the contract. If the first set of five numbers before the decimal point are the same with only the numbers after the decimal point different, it is one master contract. If the first five numbers are different, it's different master contracts.
We have two OKW contracts - one was a resale and it has a different UY than our other contracts. We have to transfer from that contract each year to make it easier to use those points with our other existing points.