hi experts，

when we enable the feature of item substitution, we try the plan group/priority and other setups, but pity for us, the feature only use for same plan groups of item. we want to realize multiple item substitution(two item as one set), such as A and A1 as one set, B and B1 as another set, if when A lack, A and B have a substitution， as the same time, A1 and B1 also have. not to consider the A1 inventory.