Word can't automatically insert commas between multiple
footnote/endnote numbers. You'll have to insert the commas
yourself manually, and format the commas as superscript to make
them line up with the footnote/endnote numbers.

bonecrusher wrote:
I need to insert multiple reference numbers after a line of text, e.g. the
optimal fixation of femoral fractures is with the technique of retrograde
nailing ^1,2 however I can't figure out how to get the commas to appear
between the numbers when I insert multiple endnote. It looks like I am
citing reference number 12 instead of 1, 2.