pdbslot works on 'Block value' which applies the change to all blocks, whereas you need to apply the slot at the instance level. This can only be done the hard way by setting the pin number for each pin as an instance level, or you can direct the packager to put all of the devices in the same part by using a Pkg Group property on the symbol and giving it a value, it can be any alphanumeric string. If you have too many slots in the Pkg Group there will be a warning issued and you will have to determine how to proceed. Before applying the package group remove the slot information from the symbol by using pdbslot and setting it to 'none'
Thank you very much