Saharasjj,Not sure I understand your question correctly, but I think you mean that one party pays 3y CMS rate (plus a spread) and the other pays 6y CMS rate (where CMS = constant maturity swap).If that is the case, you need to look into CMS pricing. It's possible to statically hedge a CMS with swaptions. You can compare this with Libor in arrears, which can be statically hedged with caplets. In the CMS case there is a slight model dependency, but the general idea is the same. As always, the treatment in the book by Andersen and Piterbarg is excellent. Best of luck.