Hello @ChrisParr1
This is a great question. First, configure the LsAgent to the settings you desire. Those assets will be pulled into Lansweeper and will able to be modified/updated when AD is scanned -- or visa versa.
Secondly, you'll want to setup a scan target for either AD Domain or AD OU. Lansweeper will automatically match the appropriate assets and merge the scanned data as you stated in your post.
This would also mean that you only have an AD scan target and not an IP Range target.
Lastly, to prevent "Scanning Access denied. Username(s) tried:..." errors, ensure the scanning that's occurring through AD has the appropriate permissions. For AD, it only needs read access. This way, the AD read-only credentials will gather the AD info as you desire, Lansweeper will also scan the asset via LsAgent, and Lansweeper's logic and technology will merge the data for each asset.
Give that a try and let us know how it goes.
Tim N.
Lansweeper Employee