Disabled and enabled copy constructors and .dup

[Per Nordlöw via Digitalmars-d-learn]

If I have a `struct X` (container in my case) with disabled 
copying (postblit) and instead a .dup property, is it somehow 
possible, unsafe or not, to have `X` as a member of another 
`struct Y` with an enabled copy constructor which calls `X.dup`?