Within independent-cluster-emission models, we study the constraint imposed by charge-transfer data on M, the effective number of charged particles per cluster. For definiteness, we consider a simple B-cluster model, which admits the emission of both the neutral and the charged clusters. By varying the relative emission strength, M is allowed to vary from 2 to 3. We find that for either neutral or charged clusters, we may have the predicted charge-transfer dispersion proportional to the single-particle inclusive cross section. Furthermore, the available charge-transfer distributions at α=0 can also be fitted for various values of M. However, as M is lowered from 3 to 2, it is necessary for the Gaussian width of the decaypion rapidity distribution to vary from 1 to 1.6. Our results combined with another independent analysis show that the B-cluster model with M=3 constitutes a simple model which reproduces many features of charge-transfer, two-particle-correlation, and gap-distribution data. The solution gives the correlation parameter within a cluster: R=〈M(M−1)〉〈M〉=2. This value is similar to that considered by others based on Poisson-type decay models.