A method and oligonucleotides for targeted nucleotide exchange of a duplex DNA sequence, wherein the donor oligonucleotide contains at least one modified nucleotide having a higher binding affinity compared to naturally occurring A, C, T or G and/or binds stronger to a nucleotide in an opposite position in the first DNA sequence as compared to a naturally occurring nucleotide complementary to the nucleotide in the opposite position in the first DNA sequence.