Can we afford a home?

If you buy the house from the parents now, you don't have to pay out the siblings. Back then, the house was supposed to be transferred = gifted. And you don't hear anything about the extension anymore. The plans have clearly been revised.

says who?

if you buy far below market price, I would proceed as a sibling due to advance inheritance

Am I actually the only reader here who wonders how

What income do you have (gross/net)? 4100€ net + a 13th salary of 2000€ net.

and

[*]Are children planned? Not at the moment, but within the next 5 years

fit together? If a child comes in five years, 35% of the assumed 2000€ of the woman will be lost – leaving 1300€ – with rising costs. Sure, this can be partially compensated by shifting tax classes, but then it has to be spouses.

I also think that the approval for a loan will not be a problem, but regarding the planning, there are still some other aspects here that are currently – out of youthful carelessness? – simply ignored.

yes and?
If you then calculate with the assumed net income of ~3,300 euros -1,000 euros loan -400 euros additional costs, 1,900 euros remain for the household.
That’s enough to get by well if you don’t go on vacation 5 times a year.

My point is that parental leave changes the income streams once again, but expenses increase. This has not really been mentioned here so far. I understand that theoretically the calculation still works out, but I already have a few question marks with the current calculation.

Besides, we are not talking about a new house here, where something can always break and reserves are needed. One thing leads to another...

that's true. However, as a rule, one is not on parental leave for the entire repayment period. Usually, salaries also increase. A household income of 4100,- Euro at that age is already very promising.

says who? if you buy far below market price, I would proceed as siblings because of advance inheritance

We have to rely on the OP here, she wrote: purchase price €170k, estimated value: €200k. That is at least a sufficiently similar amount, so that the siblings should at most feel slightly disadvantaged. In five years, income will hopefully have increased to some extent (even if only as a compensation for inflation). During parental leave, some expenses (e.g. canteen meals, commuting to work, but also "leisure activities" like dining out) are reduced. In my experience, you get by with less money there. However, I have never had to buy expensive baby formula, I admit. It only gets interesting after parental leave with part-time work, daycare fees, etc... THEN you need more money...