Hi @abs_setian,
I'm not quite sure I understand the reasoning behind a hidden 3rd row, but I believe the situation you are presenting is about positioning each row relative to the previous row or to the container as a whole. If this is the case, you could use percentage values to align each label to a relative position of the container rather than a specific coordinate, or the lv_obj_align_to() function to align an object relative to another object. Both of these possibilities are described on the following site: Positions, sizes, and layouts — LVGL documentation
With respect to identifying child objects within the container, the simplest way to do so in GUI Guider would be to pay attention to the order that the objects are arranged on the Widgets menu. This menu arranges children by descending order. Therefore, for this arrangement of the labels inside of the container:

- Label_1 is child 0
- Label_2 is child 1
- Label_3 is child 2
- Label_4 is child 3
If the number of labels inside a container is too large, you could also nest containers inside of the main container, which would allow referencing for each label to be similar to a grid. The first layer of child object would be the row, while the second layer of child objects would be the column. For example:


In this case, child 0 of the child 0 of the main container would be label "x0y0", and child 2 of child 1 of the main container would be label "x2y1".
I hope this helps!
BR,
Edwin.