I think an agreement to support the elderly written like this has legal effect:

1. It is not allowed to stipulate conditions for the performance of support obligations. Supporting parents is a child's legal obligation and cannot be subject to any conditions. For example, a caregiver may not exempt himself or herself from the responsibility for supporting support on the condition of giving up the right of inheritance, and the caregiver may not measure the size of the obligation based on the share of the parents' property. If similar agreements are made between the caregivers in the agreement, the agreement or related provisions will be invalid.

2. The property of the dependent shall not be disposed of. An agreement signed between caregivers shall not dispose of the property of the dependent. The dependent's property can only be disposed of by the dependent, and even his children have no right to dispose of it without the dependent's consent. If there is a similar disposition in the agreement, the agreement or related provisions will be invalid.

3. Obtain the consent of the dependent. Agreements signed between caregivers regarding the performance of support obligations must obtain the consent of the dependent. If the dependent no longer has full capacity for civil conduct, the caregiver must sign a support agreement.