Exposed references in PropertyDrawer

Hi all!

I'm testing the default playables asset store package and with the included TransformTween playable there are two exposed references (transforms).

The thing is that in his custom property drawer we are not referencing this exposed references but they are currently shown. In my case I want something similar, but I want to have control to show this exposed references in the inspector only is a bool is selected and in the line that I really want (not at the end as right now)

How can I achieve it?

thanks!

Sergi