Had another thought..(again photo would help )
When you speak with an expert..,ask if posts could be driven down into the land along the back edge of patio to prevent further slipppage... These same posts / supports could be used to attach lumber (or metal) to create a long bench to span across the back....or a long planting box for ornamentals / beauty or functional - veggie and herbs ( providing you have proper light) and then you would hot need to see the lack of grass.. ..the patio slipping may be stabilized... And that existing 3/4 inch opening against your house where the patio separated could be filled in with a pretty pea gravel.
