Hi, if you use data element CK_VERID (like in MARC-FVIDK), this has check table MKAL. This has three key fields MATNR, WERKS, VERID.
So you need to define an Type3 entity ZZVERID (data element CK_VERID) with leading relationship from MATERIAL and PLANT to account for the two additional key fields. Then, a referencing relationship should be allowed.
Regards, Ingo