Is it feasible to buy a second house with a mortgage on the first house?

Which post are you referring to?

He means your opening post. I quote myself:

There are often occasions in someone's life to consider a seemingly "lucrative" offer, whether from an acquaintance, a colleague's girlfriend, or as here, relatives. Often, one thinks they can better position their financial status or later make a big profit through investment. However, most do not think about the fact that they have to advance financially.

.. and actually cannot afford it. Those who are not in a position to ask, do ask – and are therefore far from reality.

It also comes into play that if you eventually rent out the house you're buying, you have the full cluster risk: if the tenant doesn't pay, you’re left in a bind and have to cover the installment from your regular income. I would say: hands off.

It also comes into play that if you ever rent out the house you buy, you have the full lump risk: if the tenant doesn't pay, you're stuck and have to cover the installment from your regular income. I would say: stay away.

Well. If someone gives you a house worth 450k for 250k and then lives in it for a few years, you refuse? Sell the shack after the right of residence expires. No lump risk and 200k in the bank.

Well. If someone gives you a house worth 450k for the price of 250k and then lives in it for a few years, do you refuse? Sell the place after the right of residence expires. No concentration risk and 200k for the account.

Yes, you refuse if you have to live in a worst case for the next 20 years because the income does not allow it.

Well. If someone gives you a house worth 450k for the price of 250k and then lives in it for a few years, do you refuse? Sell the place after the usufruct expires. No concentration risk and 200k for the account.

It is explicitly stated that the house is to be rented out "afterwards," cf. initial post.

He means your initial post.
I quote myself:

.. and actually cannot afford it.
Those who ask are not the ones in the position to ask – and therefore are out of touch with reality.

Good evening,

I must admit that I did not understand your last sentence.
But yes. At the moment we cannot afford it. Starting October, or possibly a few months earlier, it might work.
But we will see what we decide.

There is also the added factor that if you eventually rent out the house you want to buy, you bear the whole lump risk: if the tenant does not pay, you are left in a difficult situation and have to cover the installment from your regular income.
I would say: hands off.

Exactly. And precisely those kinds of scenarios we want to avoid. That would really be a disaster for us. So there must be a realistic and thus feasible structure in place beforehand. It is not called "noblesse oblige" for nothing. (A bit exaggerated).

Yes, you decline when you have to live in a worst-case scenario for the next 20 years because the income does not allow it.

And we must not forget that the gentlemen, thank God, are still very healthy and fit.
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It is explicitly said that the house is supposed to be rented out "afterwards," see initial post.

Exactly. So if we go through with this, then definitely to rent it out. We do not want to live in it ourselves. Our daughter should possibly use it later for herself.