The only real nasty I see, and it can be a deal breaker, is the fact that you have always kept your daughter in an
International School. This gives the impression that regardless of your tenure here, it was never viewed by ICA as being permanent, hence the International school gives the wrong impression.
If you search the archives here hard enough back 15 years or more you can learn what a problem it became for a certain card-carrying PAP member who has a Polish wife (SG-PR) for over 30 years and they had two British Born children while the Father was working in the UK as an investment banker on High Street for a Japanese Bank. When they came back to SG, The daughter was made a PR and went through the local system (she is now around 40 and is the MD of the father's company as the father now has health issues) The son, however, was put on a Student Visa and when through the
International Schools here and both children went back to the UK after graduating to go to universities there (One at Cambridge and the other at Oxford). Now the problem. The daughter got her law degree from Cambridge and did her 6 months with one of the best legal firms in Singapore (Daddy's connections). The son did his BS and MS in Civil Engineering and when he came back to work in the company, his EP was rejected, and no matter how many times we tried or high the salary was, it was rejected. Why? In his case he didn't do NS as he wasn't a PR here and was a UK citizen so wasn't required to do NS. The problem was the government was aware who his father was and the reason for the Student Visa was to avoid NS. I told him (the Father-who was my boss) what was going to happen when the son was only 14 years old if he persisted-his son and my son were the same age. Every rejection came back with the same reason. (You have Unresolved Issues with MINDEF. Get them sorted out first and then reapply). I retired from the company 6 months before covid after 15 years with them. We created a new Company in Myanmar and made him the MD of that company where's he been since around 2018. He can still come to Singapore on a Standard Tourist Visa, but they will not extend it. ICA and MOM have VERY LONG MEMORIES.
Basically, you appear to be creating a way of avoiding your daughter becoming a Baby Oven for the Singapore Military. While there is nothing wrong in what she has done, it probably appears to ICA that you had ulterior motives. What isn't obvious in your ample data provided is whether or not she has PR considering she was in the international school.
As a side note, With regard to volunteering with the GRC, only do so if it is something you feel strongly about, and not as a way to gain brownie points as it is no long a benefit. Certain nationalities here burned those bridges a dozen years ago in their quests to gain PR and/or SGC by volunteering with the various government link or religious groups then leaving shortly after gaining their PR/SGC. Now it doesn't mean anything to ICA at all so only do it if is something you WANT to do. (I've been a PR since 1995 but I joined the Resident Committee in 2009 and have been with them for 16 years and have been an office holder for the past 14 years. But I didn't join it for any reason other than to help my estate and our residents (I am also an anomaly in as much as I'm a Caucasian (Yank) so I kind of stand out in functions.
But, at the end of the day, continue to apply and do NOT use agencies or lawyers as I can tell you that it turns them off at ICA (I was originally rejected for my PR with a Singapore wife and 2 Singapore born children in public schools.) I made the mistake of applying via a lawyer in 1988 (this was long before online applications). After I did get PR in 1995, about 10 years later I ran into the ICA officer who interviewed me in 95 at the SICC at a Xmas party. He gave me a lot of low downs on the way they think.