Defensive offer, or have house prices become so expensive?

Which topic do you mean? The absurd increase in tangible assets? That can probably be attributed to the zero interest rate policy over which we (unfortunately) have no influence... but which might still come back to bite us. Or the romantic – and often enough unrealistic – idea that the next generations will stay in place and take over the family home? Often with deferred maintenance. In my environment, I experience both variants: sensible parents who arrange this in due time. But also the exact opposite with the classic much too large houses that get run down over the years. I firmly intend to belong to the first category later on... but who knows if stubbornness in old age won’t strike me eventually.

Just saying... grandchildren have a tax exemption of 200,000

That could be solved: Your father sells while alive and bequeaths you your share calculated based on the value from ten years ago. Or your sister "sacrifices" herself. You want to eat the cake and keep it at the same time – that is the problem.

As I said, tax advisor. I would be surprised if you had to pay even one EUR in actual taxes.

I meant more that the owners of the houses in the cities are then not the ones who live there, but some investors who mercilessly drive up the prices. Whether there are 1 or 2 houses there hardly matters.

Regionally, this does lead to socially significant changes: on the Frisian Islands, for example, heirs cannot keep the inherited house and have to sell – the islands thus fall into the hands of investors, housing for locals and workers diminishes, the beautiful houses stand empty. Businesses hardly find staff anymore or can no longer pay for employee housing. The business closes. Sylt, for example, is already bleeding under the shiny press surface. Many necessary trades no longer exist on the island. The investors don't care, but island life does.