Your contract is finished, but your RP is not expired? If you could talk to your company (sponsor) not to cancel your RP and RP's of your dependants for another few months till your daughter finish her school, and if your sponsor was willing to help you, your daughter could stay here with your brother-in-law(and as I understand with your sister), and still remain under your sponsorship. Once she is done, she might approach your sponsor with request to cancel your and your dependants’ visas.