If your relationship is sorted (descending), you don't need a portal.
However, I try to avoid sorted relationships when possible, mostly to avoid maintenance headaches, as there's currently no obvious way to determine which relationships are sorted and which are not.
So, what I might do is create a single-line portal, and sort the portal rather than the relatioship.
Im still having trouble with this
It seems to work for 99% of the customers but if a customer does not have the particular note type some other note type is showing up.
In that case you can filter the relationship or (in filemaker 11) filter the portal.
For filtered relationships include a second pair of fields for this in the relationship that only match for your specified "type".
To repeat, you can filter the relationship your portal is based on by using a second pair of fields in your relationship.