The $5000 is the federal maximum per child (provincial amounts vary). That being said, two children can transfer the maximum tuition to the same parent. There is no limit as to how many children can transfer tuition to the same parent.
Note: The tuition transfer credit is non-refundable, which means that it can only be used to reduce any taxes that you owe. If you don’t owe $5000 in taxes, then that amount won’t transfer, even if the dependant has that much to give. The dependants themselves also must use their tuition to reduce taxes payable. So they might not even be able to transfer the full $5000, which is why you need to the dependant’s tax returns first. Also, be aware that only tuition from the current tax year can be transferred.
Related Information:
TurboTax FAQ: Child's tuition credit transfer
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