It might be helpful for customers to be able to move activities in timeline from account to relationship. Not all users would need the ability but it might be helpful for admins, especially if they have to move a lot all at once.
I think we could benefit from having the Timeline object available in the mass edit feature. Not only providing the ability to move entries from Account to Relationship (because some CSMs were only logging at the Account since R360 roll up to C360 isn't yet available), but also the ability to change the Activity type, edit subject, activity date, etc... I suggest this because I can see needing to clean some of those fields up when the CSM may have selected the wrong information and it's showing as an outlier on a report.