I have a project which links to either of two other packages.
Depending on which package is being used the alternative package will
not be installed and/or will not be selected in the VBA "References"
list.

I have created wrapper classes to selectively act on objects of
classes from each of the other applications but I am still having
problems with "User defined type not defined"

The problem arises any time I try to Dim a variable as a type defined
by one of the external applications even if the code will never run
through that area (Of course the compiler/parser has no way of knowing
that)

Is there any way to have conditional Dim-ing? Should I instead be
declaring as objects and then creating using CreateObject rather than
"Dim O as New clsRandomObjectWhichMightNotExist"

Any pointers or guidelines?