Several movieclips on main timeline

Revisiting an old animation that I created many years ago with Flash & AS2.

I have several movieclips linked to the main parent timeline with a stop() action on each frame.

On each movieclip child timeline I have an action layer with a keyframe on the last frame to go to the next movieclip.

for example: _root.gotoAndStop(2)

How can I get this to work in Animate CC 2018 using AS3?

I tried this on the last frame of the first movie clip :

     MovieClip(root).mc_1.gotoAndStop(2);

then

     MovieClip(root).mc_2.gotoAndStop(3);

etc etc but

I have just started using Animate CC and not familiar with AS3 at all.

The animation is output to HTML5 Canvas.