Hello @KariK13 ,
Is there a common element linking all the contacts in that larger list, that you can easily filter them through a segmentation - something like a common tag, address, or other contact field? If so, you can use segmentation with criteria of that larger list membership AND that common element, then add the segmented contacts to the newer list.
If there's nothing in the applicable contacts' fields that'd make them easily filtered / segmented, then you'll need to go into your list and manually select the contacts to add to the newer list.
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