Mark the Words

Hi, I like the ''mark the words'' activities but I would like to be able to mark the letters also. For example, I want to ask my students to click on the letters that are not pronunced in a words.  Or we could also ask them to find the mistakes in a text, and that could be a part of word and not an entire word ...

Is it possible to modify the existing "Mark the Words" type so that I have a text box so that the student can mark the wrong word and write the correct word or sentence in that box?
If you are too busy to work on that, can someone point me in the right direction?

Thanks.

It would be great with a possibility to split up words into syllables and for the user to be able to pick a syllable in a word and or sentence that is stressed. This would be extremely usefull in language learning and I don't see any other companies offering such a solution.