WPF- Form submission with multiple child controls -

what best way submit window multiple usercontrols, each own viewmodel?

i have form, multiple child controls within it. form has viewmodel direct controls, , each of usercontrols have own viewmodel.

the number of usercontrols differ depending on user selection not same each time.

the form submitted in 1 go save button.

is case of upon save click, should loop usercontrols , save view models individually via reading datacontext? or there better way.

thanks

1. create compositecommand on parentviewmodel , pass dynamically created childviewmodels.

   public readonly compositecommand saveallcommand;

//somewhere inside parent viewmodel

childviewmodel = new childviewmodel(this.saveallcommand); 

2. then inside each of childviewmodels, register own save command saveallcommand

   public childviewmodel(compositecommand saveallcommand)     {     saveallcommand.registercommand(new savechildcommand()); } 

3. finally when execute saveallcommand in parent, childviewmodel's savecommand registered command executed well.