If you as the Sponsor wish to disclose your financial details then you can send/email your NOA, bank statements, salary stubs, etc to your relatives. They can then submit it with the Invitation Letter as part of their application.
These financial details/proofs should be photocopies. No need to notarize it. But do check with the Visa Office for the country from where your relatives are applying to be sure.
In my personal experience, none of the documents which we had submitted to the Visa Application Centre were returned to us. Hence, original documents may not be returned to you.
There is, however, an option available for you to send your financial details directly to the Visa Office in the country where your relatives are applying. In this way, your relatives would not have access to your financial details. You can enquire from CIC to reconfirm. Processing times could be longer in such cases.
invitation letter is the least weighted document as visa is granted on the applicant personal circumstances. you do not need to attach or send your bank statement.