I think you can abandon word first, let everyone use markdown or rich text, and submit it to the server after editing online.

Just don’t allow simultaneous editing~ If you really need to edit at the same time, develop a similar text comparison yourself and let the person who submitted the last submission edit the conflict by himself. If multiple people are editing at the same time, remember to remind users that "someone is editing this article"

I agree with the comment above about abandoning word. Word itself is very complicated, and it becomes very troublesome to operate it with automation or similar POI technology, but the leader probably doesn’t care about this. .
I think if you want to reserve a place, you should define a mark for all subordinate units. One mark corresponds to the corresponding part of the document. Then select the correct mark, such as the name of the unit. After submission, save the corresponding position in the document. This operation is not complicated. Writing it into a word document is relatively simple, and inserting a table is also easy.
There is no simple method for this kind of thing, of course there may be something I just don’t know. .

First of all, put aside the idea of word. In your OA, ask the leader to send the word template, and then notify the subordinate units (don’t worry about the word content and format, you only need to insert a read-only attribute after the leader uploads it (such as类别)用于识别的这次的类型并记录到数据库，然后复制分发给所有下属单位）。
等下属单位提交word回复的时候，读取文档的类别in the word information summary) Attributes, use Jacob to merge by type according to the attributes you wrote, and finally summarize them into a current file, and send the feedback to the leader