Hi Ruik,

Sequential mode is inherently setup differently than non-sequential mode in terms of positioning elements.  As the name implies, each surface is sequentially placed with respect to the surface immediately before it.  In order to mimic global positioning in sequential mode, you will need to use Coordinate Breaks with Coordinate Returns.  The concept is as follows:

• Define a global XYZ surface
• Use one Coordinate Break before the surface to position the XYZ vertex
• Use a second Coordinate Break before the surface to tilt the vertex
• Place the surface(s) you want at that given position
• Use a third Coordinate Break/Return to change the coordinate system back to the global XYZ surface

I have a LinkedIn post which describes this and also has a ZPL macro which allows you to position mirrors in global XYZ space.  If you have lens elements, then you can go back into the modified LDE and change the mirrors to lenses.

Post | Feed | LinkedIn

As for converting from Non-Sequential to Sequential, there is no built in tool that does this.  You’ll need to manually convert any file back to sequential mode.