Query children of a predecessor in TFS

I'm working in a project with a huge backlog, which structure is defined and can't be changed anymore.

In our Work Breakdown Structure (WBS) we have several epics and their user stories defined. For project reporting purposes we do have "checkpoints" defined.

Each checkpoint has a bunch of epics as predecessors. So only if we have completed all epics, we can pass the checkpoint.
In TFS 2013 I do have a query to display all checkpoints. Checkpoints are a PBI with the title [Checkpoint]. In this query, I get also the predecessors (epics) for this checkpoint.

Now I would like to get all children of these epics (e.g.):

[Checkpoint]"Infrastructure ready"
 -Link Type "Predecessor": [Epic] "Set-up TFS"
  ---Link Type "Child": [Story]"Request project in dev-ops"
  ---Link Type "Child": [Story]"Set-up Build Environment"
 -Link Type "Predecessor": [Epic] "Set-up Development Environment"
  ---Link Type "Child": [Story] "Create Docker-Container"`

Currently, I'm only able to query for the checkpoints and their predecessors. I'm struggling to get the children of the predecessors in the same query.

Adding a picture of the current situation: Query with missing children In the picture, you see that the children of the [Epic] PBI's are missing.

If you mean that you want to list all the Parent and Child work items, then you can create a type of query : Tree of work items. Reference the first screenshot for detials:

If you want to get the Parent and Child work items for a specific work item, then you can create a type of query: Work items and direct links. Reference the second screenshot for details.

UPDATE:

We can not get all work items with their parent and child work items in one query. You can try to specify the specific work item ID in Work items and direct links query, just as the example in my answer, Then you can get the three level work items related to that specific work item. We can only do this with the query, you may want to get all related work items with the three level, but unfortunately that's not supported.

You have to set-up several queries or have different ID with an OR-Query, that shoule works.