Maintaining Powerpoint Masters/Layout when importing to Storyline

Try as we might, we cannot seem to maintain the slide master from the powerpoints we wish to import to Storyline.

Surely there is a way to produce a storyline project that looks identical to the source powerpoint in its layout/graphics etc.

For compliance reasons, we need these to be a facsimile of the approved powerpoints that are the source file

Any assistance appreciated

Julia