Mutually exclusive text boxes allow you to have two required fields visible from the start, but will cause one to disappear when a value is entered in the other.
In addition to your two required fields, you must add two trigger fields and two formula fields. Give the trigger fields an initial value of 1 and set the formulas to equal a trigger field + 0.
Ex. Formula1 = [AA] + 0, Formula2 = [BB] + 0 (AA and BB being the first and second trigger field respectively)
Use conditional logic to make your first trigger field appear when any value is entered in the first required field. Then, make another rule that tells the second required field to appear when the first formula equals 0. This will make the second required field disappear when any value is entered in the first required field. Replicate these two conditional rules for your other fields, making your second trigger appear after any value is entered in the second required field and telling the first required field to appear only when the second formula field equals 0.
Both formulas will begin at 0 since neither trigger field will appear until the corresponding required field receives a value. Since both required fields are linked to the opposite formula fields, any addition to one required field will change the formula from 0 to 1, making the other required field disappear.
Eliminating the value in the required field will reset the trigger and make both available again.
*arrows represent conditional rule pointing from trigger to field to appear