Thanks for your quick responses.
@PaulS:
i don't know that - what would be the thing you prefere:
unsigned int
// or
uint16_t
i have read that the 'uint16_t' thing is the cleanest way - just harder to get for beginners?
@econjack:
thanks for the practical example 
i tried around with some 'carst constructions' but they don't woked..
i used exactly this - big to small concept.
all functions and variables for handling data were the bigest typ. so i can use this to store smaller types in them...
if - in future i want to add some other datatypes to my system - (eventually bigger than the 2byte)
i think the best way is to use a void* pointer?!
i think i than have keep track on the used size the pointer is pointing to..
could this work? or do you have some other ideas to handle such a thing?
i some way i am unsure if the approach i try is the right thing for the task..
sunny greetings
stefan