Same reference number two local libraries


I have a question with regard to the record numbers: I upload new references from my local library to endnote online, which the sharer then transfers to his own local library and removes them from the online online shared-library.

Now: Sometimes I need to make remarks/updates with regard to an uploaded document (which by now is in the local library of the sharer as well as in my own local library). They now have different record numbers.

Is there any way to have the same record numbers with regard to a document?

If not: is there any way to “mark” or give a certain number/reference to a document, in order to find it quickly?

Thank you very much in advance.

Record numbers can not be assigned, so no to first questions.  I download most of my records from Pubmed, which includes the “accession number” field which is the pubmed number.  I use this as the alternative to record numbers in my temporary citation delimiter which can be set in preferences.