Whats a good ratio of group term and private insurance? eg looking to expand the MHA aviva group term life and PA, vs having my own private insurance for coverage?

There's no definite correct answer. You can choose 30% Group Insurance 70% Private. 50|50. Or max out Group Term and get Private only if you need more.

I went for all private term. Kept the Group Term to the minimum of 100k.

However, one suggestion is to skip out on the Living Care Plus (ECI) rider. Doesn't cover enough conditions. 10 as compared to over 100 via private ECI policies.

My ratio is 33% private vs 67% group term.. mainly due to group term being much more affordable for a higher coverage quantum. Besides it covers children below the age of 10 as well.

rather than ratio, better to get covered in the right quantum for your current needs and review them time after time.