The matter is undoubtedly very exciting and interesting.
First of all, I must confess that I have not read all the statements attentively and may possibly overlook something.
Of course, one would need to know the land register excerpt and the contracts.
The situation is probably that the actual borrower (is not the property owner) has not serviced the property-secured loan for 10 years and the bank does not realize the property, or fails in two attempts due to objections by the now deceased property owner, who was possibly quite knowledgeable and clever (the bank surely has not forgotten the case). What is behind this (formal errors, etc.)? I will just put forward one assumption, a missing declaration of purpose (can sometimes be forgotten during processing?) by the property owner that the property is liable for the relevant loan of the borrower.
Then the bank indeed has a realization problem. But someone must recognize this as well (possibly the clever grandfather, even the fact that he was an influential police officer does not apparently protect him from a foreclosure auction). Because whether the court examines this matter (ZWEBE) when initiating the foreclosure proceedings is doubtful.
However, the land charge (annoyance land charge) is also present, so the property owner has a problem again.
I will now simply continue the assumed situation, then I recommend, at the appropriate time, for example as soon as one’s own occupancy is no longer existentially necessary, the following course of action.
Negotiations with the bank with the goal of getting rid of the property cheaply in order to retain the property for oneself (heirs, etc.). (Subsequently all possibilities from self-use to sale)
So for example object value €150,000, the bank has the property but formally cannot realize it, but it is in the land register; then you just negotiate at a low price level (e.g., €10,000–50,000) so that by paying such an annoyance premium you get rid of the property. Profit then for example up to €100,000 (added value of the object). Of course, the bank also knows that it is at least an annoyance to the property owner and thus will not settle for pennies.
In conclusion. I am someone who, among other things, has been financially and with expertise involved in real estate financing projects with my own means (absolutely serious and fair – references possible) for four years. In such a case I would, for example, have fun.
But everything could also be completely different. For example, realization was absolutely unsuccessful (no bidders), but it is obviously obvious from the objection that no foreclosure date took place at all, so the question remains what is behind it. Based on my experience, I have the feeling that my theory is not that far from the facts.
We could both keep an eye on this.