I've not found a way to do this.
Even if you delete the schedule and import in the same action of opening 'scheme settings', the link is broken.
That said, with drawing manager it is quick enough to relink these, if you have multiple instances of the same schedule in one PLN.
If you have multiple PLN files (as you wrote), you will have to do this for each PLN, as far as I know.
If it is 'just' quantity take off, you could possibly hotlink your model into a file with the scheme setup.
Maybe use the hotlink name as a filter to differentiate between the different master files.
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
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