Complex sentence: There's exactly one notable person on this list, and her notability is enough for an article but very minor, and there are no actual third-party sources (i.e. sources besides the Gerontology Research Group) which discuss the topic of supercentenarians in Belgium.
Split into simpler sentences: There's exactly one notable person on this list, and her notability is enough for an article but very minor. Furthermore, there are no actual third-party sources (i.e. sources besides the Gerontology Research Group) which discuss the topic of supercentenarians in Belgium.