For a 20k gift from the mother-in-law, gift tax is due.
To the daughter, it would be tax-free.
I am with HilfeHilfe and Joedereck. Your spending behavior doesn't really fit.
You have no equity. Even 20k is not enough to cover the incidental purchase costs. So you would have to finance everything. Worse conditions...
A self-employed wife makes it even more difficult to get a loan.
Not to mention, you cannot build reserves for, e.g., maintenance.
With an existing property, one must/wants to change something sometimes. You wouldn't even be able to afford any furnishing.
Therefore, rather no.