First, putting the html directly into the Page content area is not a great idea, especially if a client is going to edit that at any time. That html can go right into the page template, which is conveniently called "Page Template" in the theme editor.
Second, yes, you can set up a Page parent like you ask. For this approach, you could make a custom page template for the children -- BUT your client would have to remember to check off the correct page template choice. Then on that template you would call in the custom fields.
The fields could be managed with generic custom fields, but I think that's confusing. A better option would be to install a plugin that manages that. There are lots out there with different options, and you can tell it whether or not to display the editor (the big area with wysiwyg).
It can be scary editing template files at first, but it gets easier. Look at some videos, check out starter info on other websites (not the codex here). The best thing I learned was to first copy all the code from the template file and paste into a text file (not Word), then make my changes. If the page breaks you can always reload the first code. And be patient, the learning curve takes a little time.
You might also consider making the biographies a category with posts. Then the posts in that category could be listed on the appropriate page. You would need to set up a custom template for those posts (including the code for custom fields) then edit the Page Template to get those. This would be an if/else statement: if is_page ('where-a-list-of-bios-would-go-page-title') show the list of posts in the category of biographies, else get on with the default page styling.