I remember that sign post and tree situation--I used to walk two dogs at a time when we lived in the city and they did that end-around-let's-walk-mom-into-the-post routine, too!
I think eventually they just all got into the routine and things improved, but I don't remember how long it took or if I had a special exercise to help in the training...
Hey, what can I say? hehehe Don't get old--it does bad things to your memory!
like to request video of you with the Trio on a walk, however.