The thing is that we don't really know how the OP is planning on using their A-B units. Unless the layout owner's runs very advanced Ops sessions and has a layout with extensive number of locomotives, A-B type consists are usually permanent, and that is why (you and) I suggested using the Keep It Simple Stupid method of using address-based (aka. basic) consist. That's how I would do it, and it really is the simplest and easiest to use.
Its era dependent in my case. For the earlier era, the FT sets are always AB. Sometimes ABBA, sometimes FT AB- F2A, but the FTs are drawbar coupled and don't wander. By the time we get to the mid '60s or later though, the F7Bs go where ever they're needed, often without an A unit. Those will definitely need unique addresses.
The instigating even for this was trying to speed match an ABBA set of FTs. To do that they need separate addresses. While I could change the B unit after speed matching, I'm not sure I really want to.
