From the attached image, it seems that the proportions are almost the same, so it could certainly be done the way pinguin answered. However, if the joints are partially in different positions, you may want to use skin constraints to alter the proportions of a character. Here is a tutorial on our blog:
Blog: Skin constraints for different proportions
Also, you can watch an archive video of the stream where Erika demonstrated it here:
I hope this will help you.