How to create a custom bibliography and footnote style in Word? (2016 or 365)

Creating your own bibliographic style is hard. Microsoft's "documentation" is essentially useless. It doesn't even document differences in Microsoft Word versions. IMO the best attempt to create something that people could use to create their own styles was by Yves Dhondt and that was quite a long time ago. A Github site, https://github.com/codingo/BibWord tried to ensure that that work goes on. It's certainly worth a look, but even starting from there, creating a new bibliographic style that works the way your school wants is likely to be difficult. And you asked this question a month ago.

However, the real problem comes down to the absurd requirements of these bibliographic standards and equally absurd expectations of academic institutions. It's not that trying to standardise is a bad thing, it's trying to standardise down to the punctuation mark level was never going to work.

My suggestion to you, if it's not too late. Do what you have to do to satisfy the requirement (maybe you have to use something like Latex to do it, I don't know). Arguing with academics on this kind of issue is a complete waste of time and energy. They know they are right, and no student will change that.

I wish you good luck.

Here is Microsoft's page on creating a custom bibliography style:

https://learn.microsoft.com/en-us/office/vba/word/concepts/objects-properties-methods/create-custom-bibliography-styles