I have an existing patio with a pergola that has three original concrete sections that were separated with redwood 2X4s. The original slabs are not at the same level and the 2X4s need replacement. Also the two original slabs that are not at the same level need to be drainage sloped to match the original slab that ends with a strip drain down the middle of the original and new slabs. All of the original slabs need to be to be sealed with a decorative finish as well as additional slabs that have just been installed. The question is how to proceed.