Dianna,
Hi, yes it is complicated, do you have them or their family turning up in later census documents. If you are lucky you might get some visitors.
Yes, if you don’t already know the three words, of, in, at tell you a lot.
Of - usually the owner
In - tenant
At - worker
So the Milne’s should be the tenants..
Yes I have a few who only appear in Mort cloth records at their death. It depends on the record keeping. It’s worth researching what the quality of the parish records are, where there are gaps etc. the are a few who I have found who have fallen in those gaps.
Also as you say the session records, they can be quite informative.