Sky Tax allows the attachment of an additional letter or document that has been set up in the system as a template. There is another option that allows the attachment of additional documents as indicated in the screen below..
 

By clicking on the document icon as indicated above the user may navigate to any document on the system in use and attach it to the email going out.

Any number of documents may be attached to the email. It's always best to attach PDF documents.

By clicking on the merge it will take all the documents and merge them into one document. If the merge option is not ticked then each document attached will be separate in the email.