Peter, those are all good questions. You can put whatever you want into the Parentage field. If only one parent is known, it's okay to put just the one parent in.
The system is limited to cultivar names only. So species level names will probably not form a link although it's possible that I may extend the system to support that in the future.
banker07 said:if there is a known parent but it isn't yet in the database; what will happen if you add the parent-plant later.....
At that time then the name should become clickable. Until then it will be just a text name with no hyperlink.