Generating XML Sitemap when part of site is WordPress part is not

I am migrating to a new host from a stoneage host. All my webpages are presently .php pages which is quite a hassle. I will be putting my site on WordPress. However, there are some .php pages that I will need to recreate using the file manager (they are pages that I do not want to risk doing a redirect on at this point and time). As .php pages, I cannot create them in WordPress.

What I am curious about, is how am I going to create an XML sitemap when part of my site is not contained in wordpress? I’ve played around with a plugin and see that it generates the WordPress pages into an XML sitemap. But my filemanager created .php pages do not show up. This has been with my test site on new host – I have not actually done the migration yet.

Is there a plugin that can handle this? Is there a way to manually supplement the XML sitemaps generated by WordPress plugins and submit to Google and friends as second submissions?

I don’t expect to be updating the .php pages much. They are vestiges of the old host/situation that I am not willing to risk redirects on at this point.