Edit: too slow, but maybe useful anyway.
... während "in remainder" sich eher auf das zu beziehen scheint, was nicht anderweitig vermacht wurde.
As you can see from the definition above, that is not what remainder means in this context, i.e. it is not what's "left over" from an estate.
For example, a person, D, gives ("conveys") a piece of real property called Blackacre "to A for life, and then to B and her heirs". A receives a life estate in Blackacre and B holds a remainder, which can become possessory when the prior estate naturally terminates (A's death). However, B cannot claim the property until A's death.
The term "heir in remainder" seems to be EU terminology that doesn't appear to actually be used in British or American law.