APO SNP Subcontracting with multiple production versions/PDS

We have a need for vendor capacity leveling for our SNP based subcontracting in APO using SNP PDS. In this scenario we have two alternative
resources. This can be modeled either using multiple routings or alternative sequences for work centers. My understanding is that SNP PDS does not support multiple modes for alternative sequences. Next option is to have multiple production versions for subcontracting. When we create subcontracting purchase info record in ECC we have option to enter only one production version. I am not sure how to link multiple production versions to one subcon purchase info record, so that it can use alternative subcon resource (when resource-1 is fully consumed it should offload to resource-2). Appreciate any suggestions from experts.

Thanks in advance.

Raj