higher1871,
The reason the documentation doesn't make reference to the "criteria" you're asking about is because you don't need to know this detail to achieve the result you describe here.
As mightknowsomething mentioned, service group dependencies can be used to control the group behaviour - ie: dependencies are the mechanism to control group behaviour.
If we call the groups A (load 50), B (10), C (10), D (10) - from what you described, you basically want A to be online before B, C, D are evaluated to go online.
Look at the descriptions of online global soft or online global firm dependencies (depending on whether you want B, C, D to be restarted/remain online if A faults) - would basically be making A the child and B, C, D would be parent.