Final state strong interaction constraints on weak D0 -> K0S pi+ pi- decay amplitudes

Weak decay tree and annihilation - t-channel W - exchange amplitudes for the D0 -> K0S pi+ pi- process are calculated using quasi two-body QCD factorization approach and unitarity constraints. Final state strong kaon-pion and pion-pion interactions in S, P and D waves are described through corresponding form factors including many resonances. Preliminary results compare well with the effective mass distributions of the Belle and BABAR Collaboration analyses.