Boundary trees to be cut by neighbour

[GnarlyBob]

I'm late to this conversation but you should seek professional advice.

To cause subsidence the trees would have to be drying and shrinking out the soils underneath the foundations of your neighbours property and then causing localised collapse. This is often exhibited by cracks along mortar lines within the external skin of a masonry property. Is this occuring?

You need to deduce if the soils are shrinkable? Do you know the soil type? Have you been given a report on your neighbours property?

How far away are your trees from your neighbours property?

What species of tree are they and what water demand do these species have? What is their zone of influence?