It sounds a bit like you have the page linked rather than anchor linked, but I can't tell without seeing the website or you sharing the links that you've added. If that's right and you have a page in the index linked in the header like this /page-section rather than #page-section then it will just display the section as a page rather than part of the index.
You're actually using Squarespace 7.1 and I see that you've created this team page by adding individual Image Blocks and Text Blocks to the page. That's great when you initially build the page but, as you've found, it can make them difficult to update.
As you're on Squarespace 7.1, you can use an 'Auto Layout' section to create a team page instead. If you click Add Section and then click on the People category, you should see a number of different layouts, like this:
The guide that I've linked above explains how to use these Auto Layout sections.
If you'd like something with unlimited capacity, you could use the method that I described in my earlier post above instead.
Let me know if you need further advice.
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