Final answer:
The number of members in each lepton family must remain conserved during particle interactions, upholding the conservation laws of leptons, although neutrino oscillations can lead to variations in lepton family numbers.
Step-by-step explanation:
For leptons, the number of members in each family must remain conserved. This is according to principles such as the conservation of total muon family number and the conservation of total electron family number, which state that these quantities remain unchanged during particle interactions. While the total lepton number is generally conserved, lepton family numbers, such as electron-lepton number Le, muon-lepton number Lu, and tau-lepton number L, must be conserved separately.
Notably, while these conservation laws hold true for many interactions, they are not absolute, as neutrino "oscillations," where neutrinos transform from one family type to another, can result in variations of family lepton numbers. Nevertheless, particle experiments and the observed decay processes heavily suggest the importance of these conservation laws. Among the three lepton families, in any given interaction involving leptons, the respective family numbers must remain consistent.