Shelley,
Thanks so much for getting back to me! That really helps!

It does sound like your oldest places in Preparing.

We are doing Preparing this year and REALLY enjoying it. In the beginning, it may take several weeks to a month to hit your stride, causing your day to be longer than or equal to 4 hours, but once you do hit your stride, your day will be shorter than 4 hours! We are getting done MUCH more quickly than that now, and I cannot believe how much my son has grown and changed. Just know there is a learning curve with any new program.
With your 5 year old, LHTH will fit well and is very short each day. I would start LHTH along with Preparing, in order to get your 5 year old's skills coming along. That way you'll have him ready for LHFHG and can take 2 years to complete LHFHG with him if needed.
As far as your 7 year old daughter goes, if you place her in LHFHG, you could start out at half-speed to hit your stride, but then should probably move up to full-speed to wrap up the program in a timely fashion (due to her being on the upper age end of that program).
If you place your 7 year old in Beyond, you could stay at half-speed if needed spreading it over 2 years, as it would fit her better age-wise and expectation-wise for her age.
Since your daughter is between LHFHG and Beyond, I'd weigh how well your daughter does listening to read-alouds with few to no pictures and a little bit lengthier text, such as short chapters. These would be books that you are reading out loud to her. If she does well with that then she could go into Beyond, if she doesn't, then I'd go with LHFHG to build those skills.

For example, what has she been doing as far as history and science go up to this point? That would help me know better where she's at in those areas.
Also, what will she be doing for math? Are you planning to use Singapore or a different program? That will also help in placement too.
If you get a chance to pop back in and let me know what you're thinking as far as your 7 year old goes that would be great!
Blessings,
Carrie