I believe if you confirm WmDeployerResource package installed across all your wM versions and use WmDeployer912 you can definitely promote the packages backward compatible from Source 9.x packages to target 912 via Deployer9.12.
Please check the current setup with your admins also and capture info from the logs.
Alternatively time being, you can follow as Mahesh suggested using replicate folder options.
HTH,
RMG
#Integration-Server-and-ESB#webMethods#edi