Liran,
The table "module_name_field" controls how the Record Browser displays fields. What you are looking for is value: extra - can be 0 or 1. If this field is 0 it means that it will be shown on the main form. Extra = 1 - it will go to the Detail page (one of the page splits - to be precise).
That's not the end though: field "position" controls the order of fields, including pages. For example:
last_field_from_main_form - extra=0, position =10
field1 - page split - extra=1, position = 11
field2 - extra =1, position = 12
This should work
However this will not work:
last_field_from_main_form - extra=0, position =10
field1 - page split - extra=1, position = 12
field2 - extra =1, position = 11
Because field2 should go to the detail page, but the page split has position 12 and it will ignore all fields with position lower than 12. I hope you understand the concept.
Playing with those values you can move the field to the main form as well:
last_field_from_main_form - extra=0, position =10
field1 - page split - extra=1, position = 12
field2 - extra =0, position = 11
Here we tell RB that field2 should go to the main form (extra=0) and it will work because the position=11 is lower than the page split (12).