How do I dynamically create functions that are accessible in a parent scope?

Here is an example:

function ChildF()
{
  #Creating new function dynamically
  $DynFEx =
@"
  function DynF()
  {
    "Hello DynF"
  }
"@
  Invoke-Expression $DynFEx
  #Calling in ChildF scope Works
  DynF 
}
ChildF
#Calling in parent scope doesn't. It doesn't exist here
DynF

I was wondering whether you could define DynF in such a way that it is "visible" outside of ChildF.