How can I do to change the number of sub-populations for the migration operator?

3 Problems in the implementation of GA (Genetic Algorithms) in solving the CAP (Channel Assignment Problem)

I have some questions:

1. How does the setup of the migration operator of GA Matlab library?

2. How can I do to change the number of sub-populations for the migration operator?

3. How can I do, to change the % of mutation of a mutation operator 'custom'?

Mi code:

options = gaoptimset ('PopulationType','custom','PopInitRange',[1;Celdas],...
  'PlotFcns',{@gaplotbestf,@gaplotexpectation,@gaplotrange,@gaplotselection,@gaplotstopping,@gaplotscorediversity},...
  'Display','final',...
  'UseParallel','always',...
  'MigrationDirection','both','MigrationFraction',0.2,'MigrationInterval',5);

options = gaoptimset (options,'CreationFcn',@CAP_permutations,...
  'SelectionFcn',@selectionroulette,...
  'CrossoverFcn',@CAP_Crossover,...
  'CrossoverFraction',0.2,...
  'MutationFcn',@CAP_Mutation,...
  'Generations',100,'PopulationSize',70,...
  'StallGenLimit',30,'Vectorized','on');

%%Libreria GA
[x,fval,exitflag,output,population,scores] = ga (FitnessFcn,numberOfVariables,options);

Thanks

Hector R:.