Change the license of my contributions

[ghost]

Hi!
When I submitted several new pieces to the Mutopia Project (#1059, #1060, #1061, #1062, #1063, #1064, #1065, #1066, #1067, #1068, #1069, #1070, #1071), I inadvertently chose a public domain "license", which is AFAIK problematic (or even unlawful?) in many jurisdictions (and it's no longer recommended by CC). Is it possible to change the license of my contributions for the good of the Mutopia Project and its users? (Currently I'm weighting the benefits of CC0 vs BY-SA.)