How do you maintain endnotes when copy / pasting?

How do you maintain endnotes when copy / pasting?

I work across multiple documents within Zoho Writer. I have recently noticed that when I copy and paste some text from one document to another, the endnotes I had in the original document get wiped out in the new document (the hyperscript number in the text turns into a regular number and the endnote itself disappears). I am a journalist and need to keep my citations in tact. Does anyone know how to maintain endnotes through copying and pasting?