Hi Ishani,
I am not sure on which page you are wanting this functionality to be replicated but you have to note that "Update CI" button is defined in "list_nr.htmpl" file. You may want to copy this code and try to re use accordingly to suit your requirement.
Below is the specific code relevant to the "Update CI" button i.e.
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<PDM_IF $args.KEEP.is_cab_approval != 1> // do not display the button in CAB approval screen.
<PDM_MACRO NAME=button
id="UPDATE_LREL"
caption="Update CIs"
func="update_lrel('$args.KEEP.parentFac', '$args.KEEP.TKT_PERSID', 'nr', 'asset', 'Available Configuration Items', 'Affected Configuration Items', '')"
hotkey_name="Update CIs" >
if (parent._dtl.edit)
ImgBtnDisableButton("UPDATE_LREL");
</PDM_IF>
=================================================================================