If the government enforces the Sa’ee in such a way that one is not allowed to walk back and forth the way he could previously, then it is sufficient to perform the Sa’ee in the new added area. However, based on compulsory precaution, one should not walk from Safa to Marwa within five meters of the far right side.
It is not obligatory on the son to pay money to his father to support him financially. He is obligated to provide sustenance to his father when the latter needs it. This can be done without actually giving him the money.