Well each UDT element will have the same length as the rest. Some of the members of the array may well be pointers to more data (for example your arrays that are UDT members)

You cannot really determine where in memory those pomters will point to ahead of time. So you will not really be able to block copy array elements. If you did use CopyMemory, you would copy the element data including the member that is a pointer to an array, and then you will be able to access that array member like normal. However, updates to the original array member will update the copy and vice versa. I doubt you would really want that so you are back to square one.

I believe you need to iterate through your array OR you need to change the way you store data. Before you start thinking about that though, you have to ask yourself whether the minor inconvenience of having to iterate through the elements is worse than the hassle it will be to arrange your data differently. (That is assuming that it is feasible to arrange the data another way more useful for CopyMemory to deal with).

I hope you find another way to do what you want - because I would be interested in learning the technique for sure

Regards