Unselectable vertices

I have an object with two detached, smaller objects, all of which select together as a group in object mode. However when I go to edit mode, the main body is fully editable, but the two smaller bodies grey out and are uneditable. What’s happening here?

I want to say Alt-H (unhide) in edit mode, but I’m not sure I understand what you mean by “grey out”. Also, what version of Blender?


Alt-H was the answer. Thankyou kindly!