  We theoretically investigate the merging behaviour of two identical
supersolids through dipolar Bose-Einstein condensates confined within a
double-well potential. By adiabatically tuning the barrier height and the
spacing between the two wells for specific trap aspect ratios, the two
supersolids move toward each other and lead to the emergence of a variety of
ground state phases, including a supersolid state, a macrodroplet state, a ring
state, and a labyrinth state. We construct a phase diagram that characterizes
various states seen during the merging transition. Further, we calculate the
force required to pull the two portions of the gas apart, finding that the
merged supersolids act like a deformable plastic material. Our work paves the
way for future studies of layer structure in dipolar supersolids and the
interaction between them in experiments.
