Custom Template T1 -> Template Canvas TC1 -> Custom Template T3: how get T1 from T3

I have a custom template. Let it be called T1.
It can be used on different windows in containers with different paths

inside T1 there is a template canvas TC1

Inside the canvas there is a template T3

What is the best way to access the parameters and functions of the template T1 from the template T3?

As far as I understand, the .parent link does not work for the transition from T3 to CT1
I can access the root container of the current window, but the path to the T1 template inside this window is not known beforehand

Use more than one .parent dereference. There is more than one Swing layer in between.