Good message! I have read the photo posted on Stylistic Set Substitutions: Post 3. I selected All in the ‘Generate and Update OpenType Features’ panel, then lots of Scripts and Lookups are added automatically, when I export the font as OpenType, the .ss-suffix glyphs are reserved in the OTF file, and I can select these glyphs in Microsoft Word! Thank you, FontCreator.
This problem seems solved, at least things of the font work as I expected, as I hoped. I still don’t know what do I need to operate, for OpenType Designer, that can reserve stylistic sets glyphs in a font, but at least, I knew how to solve my problem. I decide to not delete this question, in order to let other people that have same questions have chances to read this question to help them to solve their same questions.