Copyright owner releases works into public domain

[Sugiyo]

I am the inheritor and sole owner of all unpublished works by the composer Paul Gutama Soegijo. His nationality was Indonesian, but he lived and worked in Germany. I want to make these works publicly available and have uploaded a few to IMSLP with the express remark that they are released into the public domain. The scores have been marked with a cc-by-sa declaration. Will IMSLP be able to make these works available? (The composer entry still - correctly I suppose - categorises his work as being under copyright restrictions.)