Singapore question

[Kims]

I think I want to take my kids back to Singapore. This past year has been a bust with math. I have had some health issues and we had a move in November. I have a 9yo (4th grade) and 7yo (2nd grade but not reading). Looking at the placement tests I don't think my 9yo could even start in 2A. I know he is behind in this area and it's one area we are going to start focusing on hard the first of August.
I was thinking if I had to start him lower I could just cut the binding off and hand him pages so he won't even know the level, not that I am sure he would anyway.
I need to have him do the test. I really want to be all in with HOD. I have waffled back and for the past two years and I am done. I Love HOD and want to continue it.
Also my 7yo might have to redo the K level. I am not sure. He is more natural at math than his brother.
Any thoughts or suggestions would be wonderful. I want to finally find a math and stick with it. I already bought horizons for my 7yo and my 9yo is using Teaching Textbook 3 and Math Mammoth (to help him cement his facts).
I know I didn't ask a clear question. I guess my question is should I move them back and then try to push forward a bit faster. (I don't really care about grade level but I want him to be proficient) Should I just stick with what I have?
I know that I Loved Singapore when we did it for K and 1st before. I am not sure why I switched. I don't remember now. Oh I think it was the teaching time and my health. But I am all in for as much teaching time as it takes now. Especially for math since it's important.

[StephanieU]

First, remember that Singapore 6 is basically PreAlgebra. So, if you complete 6B by the end of 8th grade, then you are still on track for Algebra 1 in 9th grade (which is the normal math for a 9th grader). So, you have:
4th grade - 2A and B
5th grade - 3A and B
6th grade - 4A and B
7th grade - 5A and B
8th grade - 6A and B
So, that would work out just fine. As for the 7yo, remember that the tests are end of course exams, not placement. So, if you pass 2A, then you start in 2B. if you pass 3B, then start with 4A.
I would think your 7yo would be fine with 1A if you have covered simple adding, counting, etc. Could he do 2+3 some how (fingers would be fine). How about 4-2? If those problems could be done by the 7yo, then 1A would be a fine place to start. If not, start with the B book for kindergarten.

[Kims]

Thank you seeing that laid out was great. I still have the B kindergarten book so I think I will start my 7yo there.
As for my 9yo I wish I had a 2A to look at. I have a 1B here and I may need to start there. Which is fine. I think if he moves pretty fast in it we can move on to 2A.
So are there 2A activities in Bigger or do I need to buy something else? Like the workbook or whatever it's called. I guess I could go look. LOL