In Layout XL, how to move a instance/shape into/out of a group array?

Take the following with care, I still have IC23.1 ISR2.29, so there could be fixes in newer releases.

Group array functions are not yet complete; e.g. removing elements from a group array via Menu Edit > Group > Remove from Group gives warning:
*WARNING* (LE-105702): Remove from group command is not supported inside a group array.

A workaround is to enter the group array, select the object you want to remove, and type in CIW:
dbCopyFig(css() nil)

This copies the first of the currently selected objects (css == Car of Selected Set) into the same cellview at same position but without a group assignment.
Then delete the selected object (selection is not changed), so it is removed from all cells in the group array.
Leave the group array and you find your object outside of the group array.
Although the result is different from removing elements on normal synchronous groups (where you get an extra object for each group in the synch family), it does prob. what you want.

Adding elements from outside into a group array cell is a bit more complex, however you could follow this article:
support.cadence.com/.../ArticleAttachmentPortal

When you list the groups to add objects, you may take a few things into account:
Groups with property type="none" are normal groups, with type="syncClone" are synchronous clones, and type="array" are the group array master objects, that wrap a number of synchronous clones which form the cells of the group array. You want to enter the elements into the cells, not into the master.
To add elements to normal groups, you can just use dbAddFigToFigGroup, for 'syncClone' you need that magic with disableVXLSynchClonePopUp. This works for normal synchronous groups and also for synchronous groups that are managed by a group array.
dbRemoveFigFromFigGroup however does only work for normal grops and normal synchronous groups (here with disableVXLSynchClonePopUp), when applied to the syncClones inside a group array, the group array association is destroyed (you might use the copy/delete workaround here). To test if a syncClone is part of a group array or a "normal" synchronous group, you can check if the figGroup of the group is a group with type "array", than it is a group member cell.