What rules apply when joining two plots that have different mortgages?

The full explanation

If two Real Property Units are amalgamated (joined), and both are already encumbered by separate mortgages, specific approvals are required. The amalgamation cannot proceed in the register without the express approval of both holders of the ancillary real rights. However, if only one unit is mortgaged, the amalgamation occurs automatically, and the mortgage right simply transfers to the whole of the new, larger unit. This ensures that the security interests of banks are not compromised by physical changes to the land,.