Visio db model:How do I display categories/alternative relationshi

If one parent has two alternative children, you would normally model it with
a curve that crosses the two relationship lines in order to indicate an
alternative relationship. How do you show this on Visio?

Also, in order to create a neat modelling, sometimes you want to group
together some entities that is related as some category. How can I do this?
(If I use a normal block, it causes a proplem every time the total lay-out is
changed, as the block is not associated with the spesific entities as such)