when you have a feat like Small Blades Basics which provides two other feats on a conditional basis (quick draw and weapon finesse for small blades only) can you use it as a prerequisite for other feats like flashing weapon and double blow, applying of course only to small blades.
Yes. These are what we call 'virtual feats." You can use them to meet the prerequisites of other feats, but any restrictions that apply to the virtual feat also apply to each feat for which it is fulfilling a prerequisite. Virtual feats may never be used to meet expert class requirements.