Buying a house from grandma or waiting for the inheritance?

I can only recommend seeking legal advice and checking the [Grundbuch]. I experienced myself what happens when a family trusts that it will “just work out.” It cost us €50K and nearly a marriage.

First of all, when grandma passes away, her children would inherit anyway. So, mom, aunt, and uncle. Unless the uncle has already been paid out. But if that's the case, there would have to be a contract. You, as the granddaughter, only receive something upon mom's passing. I can only agree with the previous speakers, first check the land register! After that, you can have a well-founded discussion. You certainly have a legitimate interest. At least mom does.

If Grandma is really afraid of being pushed aside, it might also help to point out that you feel the same way. On the family’s side, the relationship seems to be quite good and actually no one (except possibly the unpredictable aunt) has an interest in her ending up on the street. But if you credibly communicate that this is exactly your fear, maybe Grandma will then be willing to clarify things. To me, it currently sounds like the problem is simply being suppressed and that it will then blow up especially badly when it can no longer be avoided. (I also see it that way, that given the current vague circumstances, there are particularly big dangers lurking especially for your parents.)

I would also try a) to clarify the status quo (land registry entries, contracts regarding what/to whom/how/why payments were made and what that means for the inheritance) and b) to get professional help with a possible resolution of the tangle. As I said, possibly you can buy out Grandma’s share (completely?) and have a right of residence registered for her until her death. Although I would still want to see whether a complete division (including with the parents) might still be possible. Naively (purely a layman’s opinion), that should actually also be possible with partly divided utility connections. (For condominiums this is normal, for townhouses there is sometimes also common property but also separate parts.) Either it belongs to one party and you pay a bit for consumption and maintenance (possibly another meter is not rocket science either) or you somehow create common property (?) There are definitely solutions that someone specialized can tell you more about.

I can somewhat understand that Grandma doesn’t want to deal with the stress anymore, but actually your concern is to resolve this as stress-free as possible and to avoid family conflict in the future. It is not about depriving anyone of their rightful inheritance.

It should also be noted that perhaps with the partial transfer to your mother and the payout to the uncle, more has already been settled than you are currently aware of.

In our family, there was a case where, with three siblings and two houses, House 1 had already been transferred to Daughter1, House 2 was still in the possession of the grandfather, but it was stipulated that Daughter2 should receive it upon his passing (I assume the others waived their rights notarially??), and Daughter3 was paid out by the other two. Ultimately, this arrangement was somewhat overturned (during their lifetime) because the daughters’ life circumstances no longer matched the plan (this was postponed for a while but eventually settled).

However, when a part was transferred to your mother and the uncle was paid out, a portion may also have been designated for the aunt back then. All the more important, therefore, to review the circumstances again and see if you want or can change anything about them.

I get terrible stomach aches when I read this. In the worst case, your parents are really screwed if it wasn't properly settled back then. Then they don't own their own house, let alone the land, and the uncle can be paid out again. So at least your mother should urgently get her act together and gather the documents.

--> How was the payout to the uncle regulated? Is there a contract? Notarized?
--> Is she listed in the land register for the property?

As a tenant, you have no right to inspect the land register. If the mother “bought” the one house back then, there must have been a contract with the notary about it, right? If the property is not divided or if there is no owners' association, then everyone owns everything. That means an inheritance community for both houses including the annex. Determining the shares is difficult because a few pieces of information are still missing. Who did the property belong to earlier (grandfather and grandmother together or only one)? Was there a (Berlin) will? In the worst case, the grandmother still owns everything (Berlin will without anyone claiming the compulsory portion), in the best case, the mother owns over 80%. The grandfather was the sole owner and the mother inherited 1/6, paid the brother 1/6 plus the share of 1/6 from the sister, and then bought half (her house). If the grandmother dies now, each of her children will again get 1/3 of her share and everyone is back on board with equal rights.