Cross posted with Allen ... Have you tried breaking your work into segments?  I would suggest that many artists create their animations in segments.  Using IK in some portions of you animation might work well, but I don't think there is a way to string a number of actions together in a continuous stream without breaking those actions into separate animations.

Another thing is, I can't imagine a tougher task than making two figures interact with each other.  Even for single frame poses it is a challenge.

Fine results can be created with Poser, I've seen a number of impressive works.  Keep learning and playing with the software.  Learn the ins and outs of the keyframe editor and learn the differences between interpolation types.  Learn to use spline breaks.  Create managable segments and consider using a digital video editor.

You don't say how long you have been working on your project, or even how long you've been playing with Poser.  There's so much to the program, I myself have only scratched the surface in animaion, and I've been playing with Poser for years.

Best wishes, and I hope you stick with it.