How do I add an "insert" imate glyph to structure in Inventor?

I see that the CAD files for 35-hole structure, such as c-channels and angles, do not include imate glyphs when I open them in Autodesk Inventor (2017). Can anyone guide me towards a tutorial or help me with the following: I wish to add “insert” imate glyphs in the squares of these structure parts to allow me to efficiently constrain screws and standoffs. I know how to add imate glyphs to parts in Inventor, but I cannot figure out how to add an “insert” imate glyph in particular. The typical structure parts (up to 25 holes) do include insert image glyphs in the squares, but not the 35-hole parts. I have searched this forum, YouTube, and other sources but have come up empty. Attached is a capture of a 1x2x1 25-hole c-channel showing an “insert” imate glyph.
Thank you.