 All three theses require an adequate clarification of the notion of a  basic physical part.  One way to do this would be to consider objects as basic, relative to a given class of objects subjected only to a certain kind of process, just in case every object in that class continues to be wholly composed of a fixed set of these (basic) objects. Thus, atoms would count as basic parts of hydrogen if it is burnt to form water, but not if it is converted into helium by a thermonuclear reaction. But this way excludes consideration of time-slices and point events (for example) as basic (spatio)temporal parts of an object. What counts as a part, and what parts are basic, are matters best settled in a particular context of enquiry.