breadcrumbs and navmenu custom link children?

Working on a site with custom menu links (sitedotcom/#) as parent links that are not clickable. I did not create the parent pages and leave them blank, rather just made custom links.

I would like the submenu pages to have what would be the parent page (if it existed) as it’s parent (in the pages Page Attributes), but can’t because the parent pages don’t exist.

For instance, we have a Members link in our navigation (visible only when logged in) that has submenu pages of: Parents, Teachers, and Board Members

As it is now, the Parents, Teachers and Board Members aren’t child pages of Members because in the Page Attributes “Members” isn’t an option because it’s not an actual page. Breadcrumbs look like:

sitedotcom/parents
and
sitedotcom/teachers
and
sitedotcom/board

Even though they are all submenu items of the custom link Members.

But we would like Members to show up in the hierarchy as follows (so the breadcrumbs look like…):

sitedotcom/members/parents
and
sitedotcom/members/teachers
and
sitedotcom/members/board

Is there a way to do that?

Is it better to create the actual parent page “Members” in WP and leave it blank while continuing to use the custom link (#) in the nav so it’s not clickable so that we can list the child page as a parent of that page? or is there a better way to accomplish this? Or should we not be trying to accomplish this and leave the pages with out a parent?

Is either way better for SEO?

It doesn’t seem to make sense (to me) to make a page if it won’t have content. Or does the fact that we want Members to have sub pages mean that we need it to be an empty page, kind of like a directory, where the Members folder only has folders in it (subpages), but no loose files (actual content on the page itself) if that makes sense?

If we make the parent pages and just leave them blank and don’t link to them, should that blank parent page have a no-follow on it or would that make it’s child pages also not be followed?

Sorry if that’s too hypothetical! Thanks in advance