joining cut-out (ik/symbols) with hand drawn in one scene

hi guys,
i’m considering joining of two animation techniques in one scene: a cut out (actually ik on symbols, characters are in many pieces) as main parts, with hand drawn (into drawing elements) to fill the gaps not covered by the cut-out elements.
i know it could be a great deal of layer management involved, so the question:

has anybody already tried to do it this way (and could kindly spill a bit of working knowledge to us)?
or has anybody possibly a few hints how to start it in the proper way?

thanks in advance.

p.s. it’s animate non pro…