Dynamic Structure Creation

Hi All.

I want to create a structure during runtime. There are 3 fields A,B,C.

During Creation of Structure it MIGHT Have any combination of components A,B,C.

How do i create that structure.

For eg: Struct 1,

A Type ....

B Type ...

End of Struct 1.

Struct 2

B Type...

C Type..

End Struct 2.

Struct 3

B Type...

End Struct 2.

So the Dynamically structure can have any components ?

PLEASE HELP URGENTLY.