Hello jazzyj,
For the first method you can partially re-use the existing information, I can suggest the following:
- export markers (via File Menu -> Export Markers command) to XML file,
- remove markers from the project,
- select all cameras and reset alignment for them,
- check all cameras in the Reference pane and define proper camera accuracy,
- run align selected for all cameras (or Align Photos with the "reset current alignment" option disabled),
- optimize alignment,
- import markers from XML via File Menu -> Import Markers,
- uncheck cameras (or modify accuracy),
- check on all markers and press update button on the Reference pane toolbar.