The change of law in Germany, mentioned in the attached article, will make seeking compensation for wrongly paid child maintenance much easier.  

This kind of litigation is very unusual in this country as child maintenance is dealt with through the Child Maintenance Service, rather than the court and disputed paternity can be resolved at the outset before a maintenance liability is assessed. 

The issue therefore only arises where the paternity is assumed, and facts are established later to concern those who believe themselves to be the parent after having believed themselves to be the biological parent and paid maintenance accordingly.  The biological parent's liability runs from the date of a child maintenance assessment and cannot be backdated through the CMS before that.