I was thinking about that, i have just maxed my green grid to 255 quads by 255 quads, and 2x2 sections, and 32 x 32 components giving me 8192 resolution then i will create then create a lightmass importantce, okay 1 landscape floor do, so what about where management button next to sculpt click on that then click on create new landscape then should duplicate move green grid across then click on create now should have 2 created the same size, then carefully align 2 together if that will help good Luck, mega ocean mega islands.