[junek]

I would be _very_, very cautious with this. The problem is precisely that the system presents itself in a way that implies more than it actually has going on. Users will naturally assume there is a real parent-child relationship in the underlying data model.

A soon as someone asks for <thing that requires the parent-child relationship that is implied to already be there>, then you have to admit that it's a smoke-and-mirrors trick and you can't actually achieve that with the data you have.

Avoid storing visual figments in your database, they'll come back to haunt you.