sorting and grouping

Belias

hi, i am trying to create the layout of a rdlc that should be sorted by choosing between 2 different fields: item no. and salesperson code.
the layout should be like this:

Item No. sorting:

---

Item: AAAAA

---

detail lines....
detail lines....
<pagebreak>

---

Item: BBBBB

---

detail lines....
detail lines....
<pagebreak>

Salesperson sorting

---

Salesperson: XXXXX

---

detail lines....
detail lines....
<pagebreak>

---

Salesperson: YYYYY

---

detail lines....
detail lines....
<pagebreak>

The sorting (or should i say grouping?) SHOULD be interactive, and the problem is to show the two different headers based on what sorting the user chooses.
is there a way to achieve this, or should i program two different reports?
the best option should be to get 2 groupheaders that changes visibility based on the sorting order, but i don't have a clue on how to do it.
thanks in advance