I recently had to look into Child Actors as a lower level due to an unrelated issue, where a user was trying to rename their Child Actors. The functionality that is feasible has already been added. Anything further would require an entire rework of Child Actor component as Child Actors are rarely ever the same instance for the entire session. Child Actors are constantly being replaced due to how they are updated.
As for the feature request not being found, this is because we removed all Feature Requests from the public bug tracker. The request is still in and it was set to Fixed in 4.14.