When I was young, my parents bought a house with an embargo on it. Previous sellers had put the embargo on to stop any of the garden being sold without their permission. When my father wanted to sell part of it for a building plot, the previous sellers wanted half the price of the plot which at that time was £1,000. After they had £500, it was probably not really worth it. I think the embargo in this case has to be written in the deeds of the property, and if they are not already there, they can't be put there. If the neighbour has not owned the property, then how could she have placed an embargo on it?