Problems combining two endnote libraries referenced in the same document

Word 2016, Endnote X7.

I received a word document from a colleague with some 150 references she made and cited in Endnote. I see that the citations in the text (e.g. [5]) become highlighted a shade of dark grey when clicked on, as well as the references at the end of the document. Therefore I do not think they have been converted to plain text.

I have tried adding in new citations, but this begins a new reference list. 

I also tried playing around with the Endnote import library features, but for some reason nothing changes.

Thank you in advance for your help!

Have you considered creating a “Traveling Library”? Endnote in-text citations create an invisible copy of the bibliographic data and a traveling library gives access to that data.

Refer to section 7 (pp. 103-106) of the Endnote How-To instructional pdf for information and instructions on creating a traveling library: