Let's consider two papers, one by authors A1, A2, A3 and one by authors B1, B2, B3. In the case of two publications by the same research group, some of the authors may be the same, some may be new… Typically, the senior author/team leader is the same, which means that A3 = B3 (in fields where the senior author is typically listed last).
Now, my question is: in which cases is it okay to refer to the earlier work by the words “the authors”, as in “the authors have shown in [ref] that…”? Is it only okay if the two author sets are strictly equal? Or is it used when A ⊂ B or A ⊃ B? Or when the first author is the same?