ofcourse you dont ask them how to design. you are hired as the designer. ask them for specifications / limitations / painpoints in the current system etc. etc. and base your design upon their feedback on actual relevant questions.
a plumber doesnt ask his customer how to plumb. just which pipes need fixin! doesn't go fix the toilet if the shower is broken :S
a plumber doesnt ask his customer how to plumb. just which pipes need fixin! doesn't go fix the toilet if the shower is broken :S