In Processbook, you can add those additional relative time markers ad hoc by dragging new Trend Cursors from the left side of a trend. I'm not sure if this would meet your needs or not.
Another option you have in Processbook is editing the Style of the Timestamp for the x-axis; both relative and partial will add timestamps for each individual X-axis tickmark although the Full timestamp does not.
In PI Vision, I believe it's an enhancement request to add additional trend cursors to a trend as right now you can only add 1.
many thanks for your reply. The partial and relative timestamp setting you mentioned is adding more timestamps to the x-axis which is absolutely what I´m looking for. Ideally it would be absolute timestamps. And more ideally this would then be implemented into PI Vision.
Many thanks anyway for the quick response!