Since it was mentioned that there is no time pressure and the wedding is scheduled for May anyway: wait, get married, carry out the gift. Problem solved?!
That would of course be possible. But as said, the waiting times for the building application to be approved and the general contractor to have time to build could certainly be allowed to pass now.
Even if marriage has taken place, one must go through the detour via the wife as sole owner. Son-in-law is not a gift in a direct line. Furthermore, the two gifts of 1/1 to the daughter and from that 1/2 to the husband should be spaced out in time as far as possible, because otherwise the tax office assumes a kind of chain gift and then wants gift tax again.
What amount of real estate transfer tax + notary costs is this about? When we told my parents-in-law about our building plans, they bought us a plot of land but then wanted the land to be registered in my wife's name. My bank advisor then told me that in the event of a divorce I would end up with nothing. This has already been discussed here. Maybe it would be better to buy the plot from my parents-in-law for the lowest possible amount?
Completely empty one would surely not be left in the event of a divorce. At least not if the marriage was a community of accrued gains. The value of the property would be credited to the other spouse as initial assets, but everything beyond that (so then the house) would fall under the accrued gains.
It totally depends. If you have your own account, the money remains yours. If you have your own property, it is also yours, no matter who lives on it. The fact is, you should seek advice on this. There are too many pitfalls that we as laypeople cannot oversee.