I could suggest an option using a trigger against the table screlation which creates an entry directly into the sm.log for example. However, if you prefer to keep that data into a table which makes this request more complex.
You have several opitons to do that.
1. Add trigger in screlation "after add" and ''after delete" to log operator and time info
3. Enable audit funciton for screlation table. You can search "Database record auditing" in your sm onlinehelp to get more detail information.