More generally, disc breaking and disc splitting can happen in a bubble tree fashion. Such multiple splitting/breaking do not concern us, because under sufficient transversality conditions, they occur only in codimension at least two in the moduli space. To set up Fukaya categories in the exact setting, only zero and one dimensional moduli spaces are needed, so the multiple bubble trees do not occur. When we make use of higher dimensional moduli spaces in the main text, the bubble trees do occur, but the codimension two condition means the deeper boundary strata do not contribute to the boundary of the bordism current, in the sense of currents.