Restricting access to drawings.

Morning people,

I have 1 project (and would like to keep it to one project if possible), with 20 circuit diagrams in. I would like to know the best way to lock 5 of these drawing down to only a certain group of people, and then the next 5 to the next group of people. I've been using domains but not entirely sure this is best practise.

so i would have:

group1 would have Restricted 1 and General domains in their profile

and group 2 would have Restricted 2 and General domains in their profile.

But the restricted drawings is set to rise to about 45 I was wondering if there is a better way to do this than creating (potentially) 46 different domains.

Any suggestions much apreciated

Regards

Andy Middleton.