Hi Tim,
I am still a little confused as to how you want to accomplish your tasks, but I can give you my workflow with a rough example and hopefully it can shed some light on this.
Layer name: Person
Fields: Methodology, Height_1, Height_2.
Default Values from the Geodatabase: "", 99, 99
When the user clicks on Collect Height on the interface, a IPage will appear with 2 buttons, Laser or Measuring Tape.
If the user clicks on Laser, the Methodology field will automatically have the word "Laser" inserted and then the Height_1 field will be made available in the attribute form. But Height_2 will be hidden and set to " ".
If the user clicks on Measuring Tape, then the Methodology field will automatically have the words "Measuring Tape" and then the Height_2 field will be made available in the attribute form. But Height_1 will be hidden and set to " ".
I am modifying the Feature's DataRow values and hiding fields from the Attribute form accordingly.
PS: I'm still using ArcGIS Mobile 10.0 and this was a just a simple example of what I do for my Sampling module.
I hope this helps.