Bug as Peer AND/OR Child (rather than one or the other)

It'd be better if I could have Bug as a Peer (of workitems) AND/OR a Child of a workitem; rather than one OR the other.

It would enable me to reflect reality better:

- Bug1 was detected as part of delivering Story A, so we log it as a child.  Some time later realise or decide we're not going to solve it before release; and change it to peer (add to backlog).

- Bug2 was reported in production, so we log it as a peer (of other backlog items). So that it can be ranked and added to sprint like any other item.