My 5yo is, I believe, a pretty typical Kinder. He recently finished 100 Easy Lessons so is reading fairly well at about a 1.5RL and we are starting Emerging Readers and will continue into next year. He's progressing excellently in Singapore Early Bird math (the old version), understands and can retell our read alouds, etc. I have no doubt he will do well in Beyond next year and plan to use it pretty much as written (with the exception of adding in handwriting, which I believe - per Miss Mason - is better done at 6yo, rather than 5yo). He thoroughly enjoys LHFHG, especially the rhymes, music, and dramatic play.
My 6yo is a whole different story. He learned to read at 3, currently reads at about a 5th grade level, inhales any and every book in sight, is finishing up Singapore 2A this week (and has yet to come to much of a challenging concept). He writes his own stories with excellent grammar, is a pretty natural speller, can memorize like a champ, and on and on. If it was just him, I'd have no problem moving him straight to Bigger next year simply because he is fully capable of it. He's just been blessed with an incredible mind. All that to say, I don't want to just give him tons of work for the sake of having more work, nor do I want him to rest on his laurels because school is just so easy. I'm hoping to find a good balance.
At this stage, I really want to keep my boys together. They're best friends and love being together, plus our family/ministry situation, I believe, would make running multiple guides more challenging. I expect I'll have to separate them in a couple years but I'll cross that bridge when we get to it.

So, my questions are:
1) How have you beefed up Beyond for a child such as mine?
2) Do you see a problem with stretching Beyond out over 1.5 years? We only do HOD 4 days a week and leave Fridays for music, art, nature study, and recitations with another family in town. I expect to just continue math and reading at full speed along with our Friday stuff.
At this point, I'm considering some/all of the following:
- adding R&S 2
- adding DITHOR 2 (I know these books would be very easy reads but I'm not convinced of my son's comprehension skills - he whizzes through books much like I do, with a vague recollection of having read something.)
- adding Cheerful Cursive (he has been begging me for months to teach him, to which I agreed if he could demonstrate diligence in his daily copywork for the remainder of this semester - this is added to his LHFHG work)
- adding Elemental Science's Sassafras Zoology (I have no problem with HOD's science at all; this is more just because my kids love animals and read alouds so I thought this looked like a neat opportunity to study something they love)
If I utilize any/all of these options, do I need to purchase the Bigger guide for the Fall?
Wisdom from those who've gone before would be appreciated, as well as insight others may see from a more objective viewpoint!
Thanks!