Sharing the concept of Pair – as created by Erik Tyrrell in the Ars Magica forums, a new Target for Ars Magica could be “discovered” as Pair. As +1 Target which is limited to two standard Individuals.
“Pair” (meaning two individuals) as a target of equivalent level to “Part” is something that would make both MuVi and flexible formulaic magic a heck of a lot more useful and less wonky.
In the context of a +1 mag adding x10 the target material size, or +2 Group allowing for up to 10x targets in an identifiable group; this range adds flexibility, but does not break any existing range. In fact it is less than what you’d otherwise get with the +1 mag bump, which makes it both clever and reasonable.
There is also the gap within the core Targets where it would be reasonable to see Pair (+1) between Individual (+0), and Group (+2). It shows a progression of scale in a manner similar to Momentary, to Diameter, to Sun, then Moon.
Logic would need to remain in the typical use of the size and material expansion, where an effect is altered to affect a Pair using this rule, and then each is expanded for increased size as well. In effect the spell design should have to pay for expansion of both targets. Or indeed it may be possible to pay for one, and not the other if only one requires boosting to affect it.
It also makes the virtue Flexible Formulaic Magic more streamlined; so I can’t think of a reason why not to endorse this.