Make yourself well known to the support staff, as often they'll have an insight into things that teaching staff don't - for example,
the parents might be verbally belligerent towards them but sweetness and light towards staff they think are important,
they might regularly see the family because they're more likely to live in similar areas due to income (whatever way you look at it, a member of SLT is far less likely to be living on the same estate or using the same bus to get to work than somebody on £16k takehome),
they could see the children outside lessons being completely different (or staff, for that matter),
know that lunch money isn't paid until the 5th time of asking,
know that a child always seems to feel sick just before a particular lesson or seeing one member of staff/when their Dad drops them off,
they could notice the child smells really bad when needing a plaster or seem to be trying to avoid taking their jumper off,
they'll see the children being dropped off and the dynamic between the child and parent/driver,
they might see a child being a bit uncomfortable when being picked up, then have to text and call multiple times to get confirmation of absence, then see something said to the child on drop off the following day that had the child's expression change, or spot a pattern when entering Late marks or checking the registers, spot that a staffmember has overwritten a registration mark, etc. Or somebody - parent, staff, whoever, might just give them the absolute creeps, which is a perfectly valid feeling to have and can be an indicator that maybe there's something they can't quite put their finger on, but is very real.
The other aspect of that is that it's harder to complete a CPOMS entry undisturbed when you're in full view, so they might appreciate the ability to swing by and tell you 'not sure if this is a thing, but...' because it takes 2 minutes rather than 10 of trying to and continually having to switch screens whilst the phone is going and there are urgent things coming in all the time, all to say that they have a feeling something isn't right, rather than a specific disclosure.
In short, support staff can be a very useful set of eyes and ears to all sorts - if they're confident that their feelings are treated as valid as being told something really worrying.