piggybacking

[clearhorizons]

Hi

I recently purchased an ed80 and want to use my st80 for autoguiding. Both scopes came with their respective mounting rings and I was advised to purchase a skywatcher medium dovetail bar to aid with piggy backing the two scopes. Do I need to purchase any additional screws and/or drill any holes? And how do I safely mount both scopes. Sorry but I 'm new to this.

Many thanks