In light of current demographic trends, such plans are understandable, and probably even reasonable. Even though they are well-intentioned, the problem will be that the 'Germans' most likely to take advantage are those who don't need any encouragement to have children in the first place; i.e. the Muslim population.
What are they going to have to pay them to do in the future? What a bunch of nanny-staters.
IIRC, the Muslim Guest workers, and their children are not German citizens, but retain the citizenship of the country of origin of the parents. So they might or might not be eligible for the subsidy. They are eligible for most social welfare benefits.
They need to outlaw women in the workplace. That will bring the birthrate up to replacement. And they need to send all the Mohammedans to a Mohammedan country other than Germany. One of these measures is as likely to be enacted as the other.