Help: Need to fill in a field on one form based on field in second form

Help: Need to fill in a field on one form based on field in second form

Form hierarchy:

PROJECT
---- WORKAREA
----------WORKFLOW

The relationship is that 1 project can have 1 or many workareas and then each workarea can have only 1 workflow

When each workflow is marked complete via the field COMPLETE? = yes, I want the associated workarea to be marked complete.  Further, the project needs to be marked complete when all of the associated workareas are marked complete.

Also- this needs to run well on a mobile device and not include anything that would prevent an iPhone, Android or Blackberry from using this.

Thanks.