I have 5 (soon to be 6) different language books for sale. They are designed to be used by parents to teach their children. I had the idea of possibly putting all 6 (the English portion / layout is identical for all, they have just been translated into different languages) into a single book for sale... or maybe putting 3 together... (3 most popular? or least popular? not sure yet)... so people would have the option of buying "singles" or buying the whole set in a single transaction as a single book.
I would like to know what you think... is this is good idea? or bad?