You've answered my question.
I was under the impression that the two scopes needed to be pretty much aligned (I thought this was the reason for the 3 point rings) and you just had to hope that there was a reasonable star in the FOV to guide on (remember, I'm a newbie to this) but what you've said (and the example in the link) tells me exactly what I thought - the relative positions have to be flex free but perfect alignment isn't required. In fact I now know that you normally want to "misalign" them to be able to make use of a good guide star. Cool! One less thing to worry about
It all makes sense when it is explained to you.
I estimate that this lowers the number of things to worry about from around 1,675 to 1,674.
It's now "easy peasy".
Thanks again