You say the usual arguments to give to only one charity don't apply to you because you want to show your support, but isn't that one of the bad arguments listed on the page you link to? If so I presume you have a good reason why you still donate to multiple charities, but also presumably most people do not have that reason (otherwise the argument would not be a bad argument). So I wondered why you have this reason and whether as a result I and others might have that reason, and if they do then you ought to amend the article on giving to one charity so that people do not give at less than maximum efficiency