Short answer is no, there isn't going to be a single pose or other setting you can apply to every hair to make it fit a given figure.  Each hair is going to have very different geometry, some will be conforming and some will not, etc.  The morph slider you are used to with clothing to reshape between different figure morphs is something designed into each and every item you own that has that morph, and items that don't have it built in would need to be converted, each and every one, separately.  Or you could just figure out how to parent a hair to a head and stop worrying about conforming...

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