## simultaneous reactions

https://doi.org/10.1351/goldbook.S05680
composite reactions, in which processes like $\text{A}\ \overset{1}{\rightarrow }\ \text{Y}$ and $\text{B}\ \overset{2}{\rightarrow }\ \text{Z}$ occur in parallel, can be called simultaneous or parallel reactions. Sometimes there is competition involved, like in the scheme: $\text{A}\,+\,\text{B}\ \overset{1}{\rightarrow }\ \text{Y}$ and $\text{A}\,+\,\text{C}\ \overset{2}{\rightarrow }\ \text{Z}$ where B and C compete with one another for A.
Source:
PAC, 1993, 65, 2291. 'Nomenclature of kinetic methods of analysis (IUPAC Recommendations 1993)' on page 2297 (https://doi.org/10.1351/pac199365102291)