@Tightslot. I was wondering about the logic behind the requirement to return to the original seat - wouldn't be a trim issue given your high load factors and the negligible longitudinal and lateral displacement, no longer a catering issue.
FA offered me 36H (from 37H) recently vacated by a lady who had moved to 36G. She was insistent in "wishing to comply with the regulations" and reclaim her seat. FA smiled in knowing sort-of way....