Spare Kids

[ZenGum]

Ali, you're a hero.
My angle would be to call the mother, ask for a return date, and if you get one that is reasonable, wait for that, but make sure she knows that if she delays again you'll have to call child protection.
(Seriously, a 5 year old has seen neither parent for a month?? and two high-school boys are left to care for three youngsters? Sheeeesh!!!)
I doubt that Child Protection would remove them, because they (CP) have very limited resources and these kids are doing "okay", in that they are not being beaten, molested or actually starved (I presume).
However, given the recent dreadful event in Sydney (2YO boy killed, apparently by his mother, body found in a suitcase in local pond, after relatives had repeatedly contacted child protection about him being in danger), child protection might be a bit jumpy and worried and remove them just to cover themselves. I doubt it.
Ideally they would arrange a social worker to visit daily or so to check things are okay and maybe help run the household, and thus take a bit of the burden off the older boys.
There might also be some charity services that would pitch in here, I'm thinking salvos or such like. Or some other extended family? I guess that there must be some kind of support available, but the lads are hesitant to ask, or don't know where.