Attaching PDF to a List or Group of emails

So this is a follow up to the thread here:

The goal is to send a group of roughly 200 emails, formatted in HTML, and attach a PDF document w/out breaking the HTML formatting.

Including the system events command A will add the file correctly, but only to one email, not the entire list. Standard Add New Attachment breaks the HTML.

Here is the code I’m working with:

tell application "Contacts"
	set gp_list to the name of every group
	set theGroup to the value of email of every person in group (item 1 of (choose from list gp_list))
end tell

tell application "Mail"
		set useSignature to signature (item 1 of (choose from list (get name of every signature) with prompt "Choose Your Signature:"))
	end try
	set theSubject to "The Subject Matter"
	set theBody to " test"
	repeat with i from 1 to (count of theGroup)
		set newMessage to make new outgoing message with properties {subject:theSubject, content:theBody, visible:true}
		tell newMessage
				set theemailadd to item i of theGroup as rich text
				make new to recipient at end of to recipients with properties {address:theemailadd}
			end try
				set message signature to useSignature
			end try
		end tell
		tell application "System Events" to keystroke "A" using command down
		--send newMessage
		--delay 1
	end repeat
end tell

--tell application "System Events" to keystroke "A" using command down