获取特定孩子的“合并”树路径

I've got a filter page where I retrieve certain children from a directorytree (through a filter).

These children are all underneath a certain parent.

So, say I have this structure:

• parentDirectory1
  • subDirectory1
    1. child1
    2. child2
  • subDirectory2
    1. child3
    2. child4
• parentDirectory2
  • ...

Through the filter I know two things: (e.g.) - all the children i need are under parentDirectory1 - the children are child1, child3, and child4.

I could perform a "path"-query from every child up to the parent, but I would like a "merged" hierarchical result, like so:

• parentDirectory1
  • subDirectory1
    1. child1
  • subDirectory2
    1. child3
    2. child4

so NOT this:

• parentDirectory1
  • subDirectory1
    1. child1
  • subDirectory2
    1. child3
  • subDirectory2
    1. child4

I have the common fields available in my sql table: id, parentId, left, right, and level. Does anyone have a clue how I should approach this?

My apologies for the strange numbering, SO is changing it to those numbered lists :-)