A common Wagn pattern is to have a Pointer in a cardtype form, where people add relationships to other cards; and on those other cards' form (which may be the same or a different cardtype), a Search which returns things pointing to that card. When people are on the card that now has a Search, we want an no easy way to add relationships going the other way.
For the asymmetrical case (i.e. parent/child, but not sibling), we could add view:Pointer, only applicable to Searches of form {"plus": ["field", "_self"] }. It offers an "add" link, and when it's edited, an edit interface similar to Pointer (but the existing items aren't editable), with a box where items can be added. When Save is clicked, the new cards is created, with newcard+field being filled in with _self.
Organization/Foundation - Topic
Category - SubCategory - Topic
City - County - State (not high pri, but if/when people are building out new states)
others?
parent/child/sibling relationships among patterns - http://grouppatterns.wagn.org/wagn/Celebration
(workaround for sibling; harder because it's symmetrical: see http://grouppatterns.wagn.org/wagn/peers+*rform )
(duplicate). discussion moved to support bidirectionality
implement bidirectional relationships+discussed in support tickets
implement bidirectional relationships+relevant user stories