The ladies have done an excellent job of helping here!

They are such a wise group of ladies with sage advice. Honestly, it is a rare 9 yo that is ready for CTC, which is why we are all being cautious here. Unless dc have done all of HOD's plans for quite a few years before CTC, most 9 yo's place in Bigger Hearts or PHFHG. This is due to the excellent incremental teaching of skills provided in these guides, especially in the LA areas of writing, reading, dictation, and narration, as well as in the areas of gradual skill-building of following multi-step directions accurately (as in performing science experiments, completing history projects, and creating notebooking pages as higher level assessments). Likewise, independence is taught in incremental steps throughout the guides, moving dc from "T" teacher directed, to "S" semi-independent, to "I" independent in skills. For these reasons, I would love to hear about each of your twins in regard to the first page of the placement chart (reading, writing, grammar, and math). Starting in a guide that is not the right placement can cause school days to become too long, as parents have to step in and do things that were meant to be done independently - and the most difficult part of all of this? That will be a pattern you are setting for years to come, and it will be your students' first impression (as well as yours) of HOD. That is why we all want to be sure your dc are accurately placed - we want you to have an awesome start to HOD!
So, here is a link to the placement chart...
http://www.heartofdakota.com/placing-your-child.php
Here are a few more general questions...
How much are your dc used to writing each day (as in quantity and times)?
What experience do they have with dictation, oral narration, and written narration?
What are some books they are reading independently well right now, and have they had formal reading instruction?
Are they ready for diagramming in grammar, or have they already done some diagramming?
Here is a thread where the differences in CTC and PHFHG are described in detail that may be helpful...
Comparing PHFHG to CTC in Skills:
viewtopic.php?f=6&t=12582&p=90658#p90658
HTH - and we'll all wait to hear back from you - we'll be glad to help with more information! Thanks!
In Christ,
Julie